CNV 1-H1TVHH '1N3WNOHIAN3 3O lN3FSLLHVd3CI VNFIOW3 H1HON
1N3W3DVNVIM 1V1N3WNOHIAN3 3O NOISIAIQ 3i[j HJTM uopmadooo ui paj^dajj
v.r. <
' ^ V f
JSAiy Y_ > 031[UIEJ \ -JB1 V'%.
43AI» S5JOUBOJj
A3AHAS1V3IDO1O3D * S'fl
VNIIO^VD HI>ION GLOSSARY
Base flow. The contribution of flow to a stream from ground water or spring effluent. Climatic year. A continuous 12-month period during which a complete annual cycle occurs. In low-flow analyses, the climatic year typically is from April 1 through March 31, designated by the calendar year in which the climatic year begins. The year begins and ends during the period of increased flows so that all flows during a single dry season are included in annual values for that year. Continuous-record gaging station. A site on a stream where continuous records of gage height are collected and discharge records are computed. Drainage area. The drainage area of a stream at a specified location is that area, measured in a horizontal plane, which is enclosed by a drainage divide. Gage height. The water-surface elevation referenced to some arbitrary gage datum, often used interchangeably with the term "stage." Low flow. Base flow or sustained fair weather flow. Partial-record gaging station. A site on a stream where periodic discharge measure-ments are collected, usually for a period of years. The data collected at partial-record stations are often correlated with data at nearby continuous- record stations to estimate low-flow characteristics at the partial-record stations. Recurrence interval. The average interval of time within which the magnitude of an extreme event will be equaled or exceeded once. The primary recurrence intervals used in this report are 2 years and 10 years. For example, if the 7-day, 10-year low-flow discharge is 5 ft" /s, then the average discharge for a 7-day consecutive period would be 5 ft /s or lower on average 1 time in 10 years, 5 times in 50 years, or 10 times in 100 years. Unit flow. Value of flow expressed in units of volume per time per square-mile drainage area. In this report, unit flows are expressed in cubic feet per second per square mile [(ft3/s)/mi2]. Water year. The 12-month period October 1 through September 30, designated by the calendar year in which the period ends. Average discharge and flow- duration data are computed using the water-year time frame. Zero-flow day. Day in which no flow occurred at a continuous-record gaging station as evidenced by a daily mean discharge of zero. Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina
By J. Curtis Weaver
U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 96-4154
Prepared in cooperation with the
The Division of Environmental Management of the North Carolina Department of Environment, Health, and Natural Resources,
Raleigh, North Carolina 1996 U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary
U.S. GEOLOGICAL SURVEY Gordon P. Eaton, Director
The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey.
For addtional information write to: Copies of this report can be purchased from:
District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services 3916 Sunset Ridge Road Box 25286 Raleigh, NC 27607 Federal Center Denver, CO 80225-0286 CONTENTS
Abstract...... 1 Introduction ...... ^ 1 Purpose and scope ...... 2 Previous low-flow studies...... 4 Description of Roanoke River Basin...... 5 Drainage system ...... 5 Major rivers and tributaries ...... 5 Major flow modifications...... 7 Impoundments...... 7 Diversions...... 8 Climate...... 10 Geology and soils ...... 10 Land use...... _^ 14 Low-flow characteristics in the Roanoke River Basin ...... 14 Continuous-record stations...... 15 Partial-record stations...... 18 Occurrence of zero or minimal 7Q10 discharge...... 18 Discharge profiles for selected streams in the Roanoke River Basin...... 20 Town Fork Creek...... 21 Hogans Creek...... 21 Buffalo Creek...... 24 Mayo River and Smith River...... 24 Country Line Creek...... 24 Dan River...... _^ 29 Marlowe Creek...... 29 Hyco River...... ^^ Roanoke River...... 33 Summary...... _^ 33 Selected references...... 37 Glossary ...... Inside Front Cover
PLATE 1. Map showing continuous- and partial-record gaging stations, profiled streams, and occurrence of zero or minimal 7Q10 flows in the Roanoke River Basin study area in North Carolina...... In Pocket
FIGURES 1-2. Maps showing: 1. Locations of the major river basins in North Carolina, the Roanoke River Basin study area, and physiographic provinces in North Carolina and Virginia ...... 3 2. Areas of similar potential to sustain low flows in North Carolina...... 4 3. Graph showing flow-duration curves for (A) the Dan River near Francisco, N.C., (site 4) and (B) Hyco Creek near Leasburg, N.C. (site 97)...... 6 4-6. Maps showing: 4. Hydrologic units in the Roanoke River Basin, North Carolina and Virginia ...... 6 5. Average annual (A) temperature and (B) precipitation in the Roanoke River Basin, North Carolina and Virginia, 1961-90 ...... 11 6. (A) Geology and (B) generalized soil infiltration groups in the Roanoke River Basin study area, North Carolina...... 12
Contents III 7-18. Graphs showing: 7. Low-flow frequency curve of annual minimum 7-day discharges using log-Pearson Type III frequency distribution at the Mayo River near Price, N.C...... 17 8. Correlation of concurrent discharge at partial-record station at Sixpound Creek near Oakville, N.C., and at the index station at Fishing Creek near Enfield, N.C...... 19 9. Relation of river miles to (A) drainage area and (B) low-flow discharge for Town Fork Creek...... 22 10. Relation of river miles to (A) drainage area and (B) low-flow discharge for Hogans Creek...... 23 11. Relation of river miles to (A) drainage area and (B) low-flow discharge for Buffalo Creek...... 25 12. Relation of river miles to drainage area for (A) the Mayo River and (B) the Smith River...... 26 13. Relation of river miles to low-flow discharge for (A) the Mayo River and (B) the Smith River ...... 27 14. Relation of river miles to (A) drainage area and (B) low-flow discharge for Country Line Creek ...... 28 15. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Dan River...... 30 16. Relation of river miles to (A) drainage area and (B) low-flow discharge for Marlowe Creek ...... 31 17. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Hyco River...... 32 18. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Roanoke River ...... 34
TABLES 1. Code, name, and drainage area of each U.S. Geological Survey hydrologic unit in the Roanoke River Basin within North Carolina and Virginia...... 7 2. Summary of selected flow modifications by surface-water withdrawals and return discharges to streams in the Roanoke River Basin study area for 1995 ...... 9 3. Soil infiltration groups in the Roanoke River Basin study area in North Carolina...... 13 4. Areas and percentages of land-use categories in the Roanoke River Basin study area in North Carolina...... 14 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected...... 39 6-7. Magnitude and frequency of annual low-flow characteristics at: 6. Continuous-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina...... 16 7. Partial-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina...... 54
CONVERSION FACTORS, VERTICAL DATUM, AND TEMPERATURE
Multiply By To obtain Length inch (in.) 25.4 millimeter foot (ft) 0.3048 meter mile (mi) 1.609 kilometer Area acre 4,047 square meter acre 0.4047 hectare square mile (mi") 2.590 square kilometer Flow gallon per minute (gal/min) 0.06309 liter per second million gallon per day (Mgal/d) 0.04381 cubic meter per second cubic foot per second (fWs) 0.02832 cubic meter per second cubic foot per second per square mile [(ft /s)/mr] 0.01093 cubic meter per second per square kilometer
Temperature: In this report, temperature is given in degrees Fahrenheit (°F), which can be converted to degrees Celsius (°C) by using the following equation: °C = (°F-32)/1.8 Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929) a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.
IV Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina
ByJ. Curtis Weaver
ABSTRACT a wide range in basin size, characteristics, and streamflow conditions. The selected streams are An understanding of the magnitude and Town Fork Creek, Hogans Creek, Mayo River, frequency of low-flow discharges is an important Buffalo Creek, Smith River, Country Line Creek, part of protecting surface-water resources and Dan River, Marlowe Creek, Hyco River, and planning for municipal and industrial economic Roanoke River. The drainage-area profiles show expansion. Low-flow characteristics are summa the increases in drainage areas as streams travel rized for 22 continuous-record gaging stations in their course in the basin. At the mouths of streams North Carolina (19 sites) and Virginia (3 sites) and profiled, the drainage areas range from 22 miles to 60 partial-record gaging stations in the North about 9,700 miles. Low-flow discharges for each Carolina Roanoke River Basin. Records of stream include 7Q10, 30Q2, W7Q10, and 7Q2 discharge collected through the 1994 water year discharges in a continuous profile with are used. Flow characteristics included in the contributions from major tributaries included. summary are (1) average annual unit flow, (2) 7Q10 low-flow discharge, the minimum average discharge for a 7-consecutive-day period INTRODUCTION occurring, on average, once in 10 years; (3) 30Q2 low-flow discharge; (4) W7Q10 low-flow The need for better understanding of low-flow discharge, similar to 7Q10 discharge except that hydrology and for improved techniques in determining low-flow characteristics of streams has become more flow during November through March only is critical as demands for sustained, high-quality water considered; and (5) 7Q2 low-flow discharge. The supplies and effective waste assimilation have potential for sustaining base flows is moderate to increased. The simultaneous occurrence of higher high in the western part of the basin as well as in demands and recent droughts in North Carolina have the eastern and western fringes of the Piedmont increased awareness of the importance of determining and Coastal Plain physiographic provinces, low-flow characteristics. respectively. Areas of low potential for sustaining Low flow is defined as base flow, or sustained base flow exist in the central part of the basin fair weather flow, and is composed largely of ground- (between eastern Caswell County and western water discharge from aquifers into streams. Discharges Warren County), where soils have low infiltration from aquifers have large spatial and temporal varia rates, and in lower regions of the Coastal Plain, tions which are highly dependent on topographic, where small streams tend to have zero flow during geologic, and climatic conditions in the drainage basin. The high variability of such conditions across North prolonged drought. Carolina and sometimes even within a drainage basin Drainage area and low-flow discharge or along the same stream results in a complex low- profiles are presented for 10 streams in the flow hydrology. Moreover, withdrawals, point-source Roanoke River Basin in North Carolina and reflect discharges, impoundments, and development in the
Introduction drainage basin complicate the characterization of low- assessment and management of water quality and, in flow hydrology. Low flows in North Carolina typically particular, permitting of point-source discharges. This occur at the conclusion of the growing season in late approach is being applied sequentially to each of the summer and early autumn, following maximum use of 17 major river basins in the State (fig. 1) so that all ground water by crops and other plants. The moder discharges in a basin are permitted simultaneously. The ation of temperatures also causes a reduction in human consumption of water supplies, which in turn places process is repeated for each basin at 5-year intervals. In less demand on withdrawals from streams and conjunction with the basinwide approach, the U.S. reservoirs. Geological Survey (USGS), in cooperation with the An understanding of low-flow characteristics is DEM, began a study to define low-flow characteristics crucial in the evaluation of water-supply potential and in the Roanoke River Basin in North Carolina for use reservoir-release requirements, the determination of in permitting point-source discharges. allowable wastewater discharges into streams, and the maintenance of aquatic habitats in streams. Where sufficient records of discharge are available at Purpose and Scope continuous- and partial-record sites, application of statistical techniques, such as those described by Riggs This report presents low-flow characteristics for (1972), form the basis for determining low-flow streams in the Roanoke River Basin in North Carolina. characteristics. However, the number of sites for which Low-flow characteristics at existing stream gaging sufficient record exists to determine low-flow charac stations are summarized, and drainage area and low- teristics is far outnumbered by those locations where flow discharge profiles for selected streams in the little or no record is available for developing estimates. Roanoke River Basin are presented. Descriptions of a Low-flow characteristics are defined by a set of number of basin characteristics (impoundments, discharges that are statistically derived values having diversions, climate, geology, soils, and land use) and an associated duration and recurrence interval (or probability of occurrence). For example, the 7-day, their effects on low flows are included in the report. 10-year low-flow discharge (hereafter referred to as Low-flow characteristics are summarized for 7Q10 discharge) is the annual lowest mean streamflow 22 continuous-record gaging stations (including three over a 7-consecutive-day period which, on average, on the Dan and Hyco Rivers in Virginia) and for 60 will be exceeded in 9 out of 10 years or stated another partial-record gaging stations; statistics include the way, the probability is 10 percent (the inverse of the average annual unit flow and the 7Q10,30Q2, W7Q10, recurrence interval) that the lowest average 7-consec and 7Q2 discharges. The period of record varies from utive-day flow in any year will be less than the 7Q10 site to site; in this report, records of discharge collected discharge (Giese and Mason, 1993). If the 7Q10 discharge is 5 ft3/s, then the annual minimum average through the 1994 water year were used in the analyses. discharge for a 7-consecutive-day period would be The number of zero-flow days and discharge measure 5 ft3/s or lower an average of 1 time in 10 years, 5 times ments for continuous- and partial-record stations, in 50 years, or 10 times in 100 years. respectively, are included in the summary. In North Carolina, other low-flow statistics used Drainage area and low-flow discharge profiles by State regulatory agencies in determining permitting are presented for 10 selected streams and tributaries in limits for withdrawals from and discharges into the Roanoke River Basin in North Carolina. The streams include the 30Q2, W7Q10, and 7Q2 streams drain areas which reflect a wide range of basin discharges. The W7Q10 discharge, or "winter 7Q10," size, characteristics, and streamflow conditions. The is defined in a similar manner as the 7Q10 discharge selected streams included are Town Fork Creek, except flow in the months of November through March only is considered in the analysis. Hogans Creek, Mayo River, Buffalo Creek, Smith In 1991, the Division of Environmental Manage River, Country Line Creek, Dan River, Marlowe ment (DEM) of the North Carolina Department of Creek, Hyco River, and Roanoke River. Discharge Environmental, Health, and Natural Resources profiles show the relation of 7Q10, 30Q2, W7Q10, and (DEHNR), began using a basin wide approach in its 7Q2 discharges to river mileage.
Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina TD C 03 03 "o_C
03 O ^: e o
CO 0 o c o Q. '^:O Q. 03 O) O
TD C 03 03" 0
03 CD
CC 0 ^ o c 03 O CC
03 "o_c
03 O .C e o
i_ -x O -^- O 0) \. ___ - f v x CD V ^i !i \ 1 Ul T3 S ^ 'c cc \ 's " I . Ul Q) \ y, C/D 3 J § 1 CD j ^ .^~ 1 Ul t-*£r < i Z o Z \ CCo _ ! H ~^) i Ul , f 1 0 < S i ! 1 1
Introduction Previous Low-flow Studies Only a limited number of studies have been conducted to investigate low flows for streams in North Prior to World War II, low-flow characteristics of Carolina. Goddard (1963) presented low-flow charac North Carolina streams were determined only for sites teristics for many continuous-record gaging stations in operated as continuous-record gaging stations. With North Carolina along with drainage area and 7Q10 the economic expansion after World War II, the USGS discharge profiles developed for selected mainstem began to receive an increasing number of requests for rivers. Yonts (1972) reported base-flow measurements hydrologic information at sites where no data had been made at over 2,200 continuous-record and partial- collected (Yonts, 1972). Thus, the USGS expanded its record gaging stations throughout the State. data-collection programs in the late 1940's to include Giese and Mason (1993) evaluated low-flow partial-record sites where discharge measurements characteristics at 518 continuous- and partial-record were made on a periodic basis. Discharge measure gaging i~\stations having drainage areas between 1 and ments made under conditions of base flow along with 400 mi and having streamflows unaffected by observations of zero flow became the foundation of regulation or diversions. Sites were characterized on data used in the initial assessments of low-flow the basis of similarity in ranges of low-flow discharges characteristics in North Carolina. With data available and potential to sustain base flow. Ten hydrologic areas from the partial-record sites network, the USGS began (HA) were delineated and regression equations, which to respond to requests for low-flow characteristics on a related low flows to basin characteristics, were derived site-specific basis, including ungaged sites. to determine flow characteristics at ungaged sites Estimates of low-flow discharges continue to be (fig. 2). Equations for only four of the 10 areas provided upon request to government agencies and HA10, representing the mountains and western private corporations. These data are used in assessing Piedmont; HA3, the Sand Hills; and HA5 and HA9, the capacity of streams to receive wastewater the eastern and central Piedmont had standard errors discharges and to allow withdrawals for water supply. that were considered small enough to permit use of the Data are generally provided on a site-specific basis equations in estimating low-flow characteristics at the without consideration of previously estimated low- ungaged sites. The large standard errors computed for flow statistics upstream or downstream from the equations in the remaining hydrologic areas reflect the request site. In some instances, this has led to complex relation between low-flow hydrology and inconsistencies in estimates of low-flow discharges for geologic, topographic, and climatic factors. High adjacent sites. standard errors for low-flow regression equations
84° 83° 82° 81C 80° 79° 78° 77° 76°
36C EASTERN AND CENTRAL 7////A PIEDMONT HA9
35C
EXPLANATION POTENTIAL TO SUSTAIN LOW FLOW HIGH 34C 0 INTERMEDIATE n LOW 100 MILES - - ROANOKE RIVER BASIN BOUNDARY 50 100 KILOMETERS
Figure 2. Areas of similar potential to sustain low flows in North Carolina (modified from Giese and Mason, 1993).
Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina also were reported in a 1970 comprehensive study of (1989), who related rock type to well yields. Thus, low flows in which 47 USGS districts participated these hydrologic areas were delineated on the basis of (each district being representative of the State in which geology. The eastern areas of the Roanoke River Basin it is located) (Riggs, 1973). Some districts reported in the Coastal Plain fall within HA1 and HA2 and have standard errors well in excess of 100 percent while low potential to sustain base flow in streams. Low others were unable to derive useful low-flow relations. topographic relief results in low hydraulic gradients in Evett (1994) investigated the effects of urbaniz the water table, with little potential to move water ation and land-use changes on low flows. Negative towards streams. A comparison of sites having trends in low flows were detected from data at selected sustained base flows versus those not having sustained urban and rural continuous-record gaging stations in base flows can be seen in the flow-duration curves for the Asheville, Charlotte, Greensboro, and Raleigh two sites in the study area (fig. 3). Base flows for the municipalities (fig. 1). However, while the conclusions gaging station on the Dan River near Francisco (site 4; tended to support the investigation's hypothesis of plate 1) are much higher than those at the gaging station decreasing low flows with increasing urbanization, the on Hyco Creek near Leasburg (site 97). During the o results were considered statistically inconclusive. 1950-94 water years, flows at site 4 were 65 ft /s or greater 95 percent of the time, whereas flows at site 97 were greater than 0.1 ft Q /s. DESCRIPTION OF ROANOKE RIVER BASIN The Roanoke River Basin drains an area of about Drainage System sj 9,700 mi in parts of North Carolina and Virginia The Roanoke River Basin consists of seven (Seaber and others, 1987). Approximately 36 percent subbasins, units 03010101 to 03010107, as defined in of the basin is in North Carolina (fig. 1). The head the system of hydrologic units in the USGS National waters of the river are in the mountainous region of southwestern Virginia, and the river flows in a general Water Data Network (Seaber and others, 1987) (fig. 4; southeastern direction through the two States before table 1). In this report, the study area for the Roanoke entering the Albemarle Sound. The nature of the River Basin is defined as the parts of units 03010102 drainage system of the Roanoke River Basin varies (Middle Roanoke), 03010103 (Upper Dan), 03010104 greatly from the headwaters to the mouth. (Lower Dan), and 03010106 (Roanoke Rapids) lying in Ground elevations in the Roanoke River Basin in North Carolina, and all of unit 03010107 (Lower North Carolina decrease from west to east. Average Roanoke) (fig. 4). Gaging stations and measurements elevations range from approximately 1,000 ft above from streams in these areas are used to determine the sea level in Stokes County north of the Dan River to sea low-flow characteristics presented in this report level at the mouth of the Roanoke River (Stuckey, 1965). The highest elevation in the basin in North Major Rivers and Tributaries Carolina is nearly 2,570 ft above sea level near the drainage area divide west of Danbury in Stokes County The Dan River, the largest tributary to the (plate 1 at the back of the report). Roanoke River, begins in the eastern fringe of the Blue The Roanoke River Basin in North Carolina Ridge physiographic province in Virginia and flows in includes parts of seven of the 10 hydrologic areas a south-southeasterly direction into the Piedmont identified by Giese and Mason (1993). The western Province of North Carolina (plate 1). The river makes areas of the basin are in HA 10 (fig. 2), where base an abrupt 90-degree turn in Stokes County and flows in flows are generally sustained primarily because of the a north-east direction into Rockingham County where large degree of topographic relief which exists in the it crosses back into Virginia. Southeast of Danville, the western Piedmont and Blue Ridge Provinces. The areas Dan River re-enters North Carolina for a brief stretch of the basin falling within HA9, HA7, HA5, and HA4 before returning to Virginia, where it eventually in the central and eastern Piedmont have intermediate merges with the Roanoke River in John H. Kerr or low potential for sustaining base flow. Giese and Reservoir. Much of the terrain in the Dan River Basin Mason reported a correlation between the potential to is characterized by the rolling and hilly topography. sustain base flow and well yields reported by Daniel The total length of the Dan River is nearly 200 mi with
Description of Roanoke River Basin 10,000
1,000 Hyco Creek near Leasburg Q Z (Site 97, plate 1) O o LU CO tr 100 LU CL
UJ LU LL
O Z Dan River near Francisco O (Site 4, plate!)
0.1
0.01 i i___i i 0.5 2 5 10 20 30 50 70 80 90 95 98 99.5 PERCENT CHANCE FLOW EXCEEDED
Figure 3. Flow-duration curves for (A) the Dan River near Francisco, N.C. (site 4), and (B) Hyco Creek near Leasburg, N.C. (site 97).
03010101 03010102
x (..,. -:' 03010105 -^
03010103 > 03010104 ' --_-- --____ "j- - 03010106.''- - -c.' j..---^.- ../;"
EXPLANATION 03010107 n STUDY AREA 'v . HYDROLOGIC UNIT BOUNDARY REGION -i r- ACCOUNTING UNIT (03[01|01J04] SUBREGION ^ ^= CATALOGING UNIT
ROANOKE RIVER BASIN HYDROLOGIC UNITS LISTED IN TABLE 1 0 10 20 30 40 50 MILES
0 10 20 30 40 50 KILOMETERS I
Figure 4. Hydrologic units in the Roanoke River Basin, North Carolina and Virginia.
6 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Table 1. Code, name, and drainage area of each a gradual transition from gentle, rolling hills with little U.S.Geological Survey hydrologic unit in the Roanoke River relief to nearly level land surfaces found in the Coastal Basin within North Carolina and Virginia Plain. [USGS, U.S. Geological Survey; mr, square mile; N/A, not applicable.] The drainage area of the Roanoke River at the Drainage area within USGS continuous-record gaging station (site 181; USGS (mi2): 1 hydrologic plate 1) downstream from the dam at Roanoke Rapids Name unit code North Vjr_ Hydro- Lake is 8,384 mi2. This accounts for nearly 86 percent Caro- ,'r." logic (fig. 4) ginia Una unit of the entire Roanoke River Basin. The 140-mi stretch between the dam at Roanoke Rapids Lake and the 03010101 Upper Roanoke [River] N/A 2,192 2,192 mouth accounts for over 36 percent of the total length 03010102 Middle Roanoke [River] 299 1,473 1,772 of the river, yet the drainage area only increases by 03010103 Upper Dan [River] 914 1,140 2,054 14 percent. This characteristic is reflected in the narrow 03010104 Lower Dan [River] 717 534 1,251 shape of hydrologic unit 03010107 downstream from Roanoke Rapids Lake (fig. 4). Major tributaries to the 03010105 Banister [River]2 N/A 597 597 Roanoke River in North Carolina include Chockoyotte 03010106 Roanoke Rapids 254 337 591 Creek, Quankey Creek, Occoneechee Creek, 03010107 Lower Roanoke [River] 1,319 N/A 1,319 Gumberry Swamp, Conoconnara Swamp, Kehukee Totals 3,503 6,273 9,776 Swamp, and Conoho Creek. The Cashie River, the (36%) (64%) largest tributary, which drains nearly 305 mr of 'Drainage areas computed using USGS ARC/INFO Geographic hydrologic unit 03010107, merges with the Roanoke Information System coverages. River in the delta area immediately upstream from the 2The Banister River is a tributary of the Dan River at John H. Kerr Albemarle Sound (plate 1). Reservoir in Virginia.
Major Flow Modifications a little more than 120 mi, or 60 percent of its total length, in North Carolina. Previous discussions have alluded to the complex nature of low-flow hydrology due to geologic, The drainage area of the Dan River at its mouth topographic, and climatic factors. An additional is about 3,900 mi2, or about 40 percent of the entire complexity in the determination of low-flow charac Roanoke River Basin. Portions of hydrologic units teristics results from the existence of major flow 03010103 and 03010104 within North Carolina (fig. 4) modifications. These modifications can be classified occupy nearly 1,630 mi2 of the Dan River Basin. Along into two general categories impoundments and the 120-mi length of the Dan River in North Carolina, diversions of flow. The ongoing addition and, in some the drainage area increases from nearly 71 mi2 at the instances, removal of these modifications results in discontinued USGS gaging station near Asbury (site 1; ^ continual changes to the low-flow characteristics. plate 1) to 2,310 mi at the partial-record station near Milton (site 80; plate 1). North Carolina tributaries draining to the Dan River include Town Fork Creek, Impoundments Belews Creek, Hogans Creek, Mayo River, Buffalo Impoundments result from the construction of Creek, Smith River, Wolf Island Creek, Country Line dams on streams, for use in storing water for a variety Creek, and Hyco River. of purposes including supply, recreation, irrigation, and The Roanoke River is nearly 385 mi long, with cooling water. The effects of impoundments on much of its length lying in Virginia (plate 1). The river downstream low-flow characteristics vary because of enters North Carolina in Warren County at Lake changes in streamflow patterns that result from storage, Gaston and Roanoke Rapids Lake, two large reservoirs diversions of water (for supply purposes) that which are impoundments of the Roanoke River. commonly occur within the impoundments, and to a Downstream from Roanoke Rapids Lake, the Roanoke smaller extent, evaporation from the impoundments. River reverts back to a riverine reach for its final Post-impoundment flow durations for downstream 140-mi meander towards the Albemarle Sound in flows, particularly below major impoundments, adjust Bertie County. The topography of the basin down in response to changes in flows relative to pre- stream from Roanoke Rapids Lake is characterized by impoundment conditions.
Description of Roanoke River Basin Approximately 360 impoundments with dams must be sufficient to assimilate the treated effluent having structural heights exceeding 15 ft were while maintaining other uses of the stream. The DEM identified in the study area (North Carolina Department has issued 366 NPDES permits for point-source of Environment, Health, and Natural Resources, discharges within the study area (North Carolina unpub. data, 1993). Many are privately owned Department of Environment, Health, and Natural impoundments having relatively small surface areas at Resources, 1996). Seventeen permit holders (eight the spillway level and serve as farm ponds, which municipal, nine industrial) are designated by the DEM provide irrigation and sediment reduction, or as as major dischargers. recreational facilities at campgrounds and park Data describing major withdrawals and point- facilities. Four of the impoundments have very large source discharges in the study area were obtained from surface areas: Belews Lake (4,030 acres) (North the different State agencies which monitor flow Carolina Department of Environment, Health, and diversions. For selected facilities, average surface- Natural Resources, 1992) in Stokes, Forsyth, and water withdrawals and return point-source discharges Rockingham Counties; Hyco Lake and Afterbay reported for 1995 were compiled into a summary that Reservoir (4,400 acres) in Caswell and Person lists the magnitudes of streamflow changes in the Counties; Mayo Lake (2,800 acres) in Person County; affected streams (table 2). In most instances, point- and Roanoke Rapids Lake (4,890 acres) in Halifax and source discharges were paired with a corresponding Northampton Counties (immediately downstream from surface-water withdrawal on the same stream, often a Lake Gaston and John H. Kerr Reservoir in Virginia). short distance upstream from the discharge point. For These lakes, owned by utility companies, are used each facility, the NPDES permit number and permitted primarily for power production and cooling water. The flow rate assigned to the permit also are listed. effect of these impoundments on downstream flows is Some of the facilities which discharge into determined by the minimum flow releases at the dams. streams do not obtain water through surface-water withdrawals. In these cases, withdrawals are made Diversions from ground-water wells (primarily in the Coastal Diversions, occurring as withdrawals or point- Plain) or are transferred from other facilities. An source discharges, have the effect of immediately additional form of withdrawal listed with the State altering downstream low flows by an amount equal to agencies is that made by large mining operations, the diversion rate. Withdrawals are commonly made by which remove ground water from mining pits and municipalities and by some major industries. Addi discharge it into nearby streams. In the study area, tionally, some withdrawals are made by farms for withdrawals by three mining operations in Caswell, agricultural and livestock operations. The State of Rockingham, and Vance Counties were registered with North Carolina requires registration of withdrawals the State. These are not listed in table 2 because with equal to or exceeding 1 Mgal/d (approximately drawal and return discharge rates are not documented. 1.5 ft3/s). Within the study area, a total of 24 registered Also not listed in table 2 are withdrawals and withdrawals were identified (North Carolina return discharges for a number of utility companies Department of Environment, Health, and Natural which use impoundments as sources of water for Resources, written commun., 1996). Knowledge of electric power production and cooling purposes. low-flow characteristics is important when with Water-use records obtained by the USGS in 1990 drawals are being made because decreased flows indicate that withdrawal and return discharge amounts downstream from the withdrawals must be sufficient to exceed 750 Mgal/d (nearly 1,200 ft3/s). Most of the sustain downstream uses during drought conditions, water removed from these lakes by utility companies is including the assimilation of treated effluent. returned to the impoundments. A small percentage of Point-source discharges into streams are the water, usually 1 to 2 percent, is consumed in the permitted through the issuance of National Pollution production and cooling process. However, this loss is Discharge Elimination System (NPDES) permits. In often replaced by water obtained from other sources, North Carolina as well as other States, permits that set thereby giving the appearance of no net loss in water limits for discharges of treated effluent are based, in quantity (W. L. Yonts, North Carolina Department of part, on the 7Q10 discharge. In a similar manner to Environment, Health, and Natural Resources, oral withdrawals, flows upstream from the discharge point commun., 1996).
8 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Table 2. Summary of selected flow modifications by surface-water withdrawals and return (point-source) discharges to streams in the Roanoke River Basin study area for 1995 [Mgal/d, million gallons per day (1 Mgal/d is equivalent to approximately 1.5 cubic feet per second); N/A, not applicable; N/D, not documented. For streams profiled in this report, river miles are listed in parentheses beside stream names.]
CO T3 i C 1= LJJ =S JO Q re o z? 3 °> _ 0. °> £1 Destination of 0) 2 County Facility name Purpose Source of withdrawal '> re 0) 0) permit "O fl) > O) return discharge o> o> c 2* 0) 5 re js O)S- number JO > u 11 CD < « 0) (0 > ' o °- =o
Rockingham Town of Mayodan Public water supply Mayo River (mile 2.5) 1.6 Mayo River (mile 0.6) 1.2 NC0021873 3.0 Rockingham Town of Madison Public water supply Dan River (mile 105.3) 0.5 Dan River (mile 105.0) 0.4 NC0021075 0.775
Rockingham City of Eden Public water supply Dan River (mile 86.0) 10.0 Dan River (mile 84 5) 6.6 NC0025071 13.5
Rockingham Fieldcrest Cannon Industrial / water Smith River (mile 1.5) 1.3 Dan River (mile 8 1.7) 0.16 NC0001643 0.5 (Eden) supply
Rockingham Duke Power Thermal electric Dan River (mile 83.5) '70.1 Dan River (mile 83. 5) 70.1 NC0003468 N/D2 power
Rockingham Miller Brewing Industrial Transfer from City of N/A Dan River (mile 82.0) 2.4 NC0029980 5.2 (Eden) Eden
Person City of Roxboro Public water supply Isaac Walton Lake3 4.4 Marlowe Creek 2.9 NC0021024 5.0 (mile 5.6)
Person Cogentrix (Roxboro) Thermal electric Transfer from City of N/A Unnamed tributary to 0.06 NC0065081 N/D2 power Roxboro Mitchell Creek
Person Carolina Power and Thermal electric Mayo Lake - Mayo River 3.3 Mayo Lake 10.7 NC0038377 21.0 Light power
Vance Kerr Lake Regional Public water supply John H. Kerr Reservoir4 5.0 Nutbush Creek 2.7 NC0020559 4.14 Water System (City of Henderson)
Halifax Roanoke Rapids Public water supply Roanoke Rapids Lake5 5.0 Roanoke River 66.0 NC0024201 8.34 Sanitary District (mile 126.8)
Halifax Champion International Industrial Roanoke River 27.0 Roanoke River 17.9 NC0000752 28.0 (Roanoke Rapids) (mile 130.0) (mile 129.9)
Halifax Town of Weldon Public water supply Roanoke River 3.4 Roanoke River 0.7 NC0025271 1.2 (mile 132.0) (mile 124.5)
Martin Alamac Knit Fabrics Industrial Ground-water wells N/A Roanoke River 1.1 NC0001961 1.5 (Hamilton) (mile 56.5) Martin Town of Williamston Public water supply Ground-water wells N/A Roanoke River 1.1 NC0020044 2.0 (mile 34.2) Washington Weyerhaeuser Industrial Ground-water wells N/A Welch Creek 69.9 NC0000680 82.5 (Plymouth)
Bertie Town of Windsor Public water supply Ground-water wells N/A Unnamed tributary to 0.4 NC0026751 1.15 Cashie River
'Flows reported for 1990 (USGS 1990 water-use files). 'No permit limits established; flow is monitored. - Isaac Walton Lake (Satterfield and Story Creeks) serves as normal withdrawal source; Lake Roxboro (South Hyco Creek) serves as an emergency source. 4Withdrawals redistributed as follows: 3.0 Mgal/d to Henderson (Roanoke River Basin), 1.5 Mgal/d to Oxford (Tar River Basin), and 0.5 Mgal/d to Warren County (Tar River Basin). Water received by Oxford and Warren Counties treated and released into the Tar River Basin. 5One intake used daily; a second is available for emergency use. Roanoke Rapids Sanitary District receives and treats wastewater from nearby small municipalities and entities; thus, average return discharge is higher than average withdrawal.
Description of Roanoke River Basin The average withdrawal and return discharge shown in the State. At the USGS gaging station at Flat River at table 2 for one utility company in Rockingham County Bahama (station 02085500) in Durham County, the using the Dan River as a source indicates identical lowest daily mean discharge (0.27 ft3/s on the 24th) and withdrawal and return discharge quantities. instantaneous discharge (0.23 ft /s on the 26th) for the period of record (July 1925 to September 1994) occurred during September 1968 (U.S. Geological Climate Survey, 1961-94, published annually). While not within the study area, much of the drainage basin for The climate in the study area, as throughout most this site lies in the lower half of Person County of North Carolina, consists of long, hot, humid summers and short, mild winters with brief periods of immediately adjacent to the study area (plate 1). more moderate, pleasant conditions during the spring Hence, flow conditions at the Flat River gaging station and autumn seasons. The average annual temperature are a good index of flow conditions occurring in the (1961-90) in the study area ranges from about 55°F region. The drought of the longest duration (1950-57) near the western edge of the Roanoke River Basin to among the seven major droughts in North Carolina, 60°F in the area near the mouth of the Roanoke River where low flows had recurrence intervals of about (fig. 5A). Records collected by the National Weather 30 years, did not severely affect flows in the study area Service at selected observation stations in and near the where the recurrence interval of the low flows was less study area indicate the average temperature ranges than 10 years. from a minimum of about 40°F in January to a maximum of about 78°F in July (National Oceanic and Atmospheric Administration, 1992). In some areas of Geology and Soils the basin, particularly the Piedmont and Coastal Plain physiographic provinces, temperature extremes in the The geology of the study area varies greatly from summer reach levels exceeding 90°F for long periods the western edge in Surry and Stokes Counties to the of consecutive days. mouth of the Roanoke River in Bertie County (fig. 6A). Average annual precipitation (1961-90) at Most of the study area within the Piedmont physio selected observation stations in and surrounding the graphic province is underlain by belts of metamorphic study area ranges from nearly 52 in. in the foothills and metavolcanic rocks dating from the late Protero- region of the western Piedmont Province to 44 in. in the zoic and early Paleozoic periods (North Carolina central and eastern Piedmont Province (fig. 5B). In the Department of Natural Resources and Community Coastal Plain province, average annual precipitation Development, 1985). Underlying rocks include increases to between 44 and 48 in. On a monthly basis, granite, granitic gneiss, schist, slate, and phyllite the highest amounts occur during July, while the lowest (fig. 6A). The noted exception is the Triassic basin amounts occur in January or February. Most rainfall across parts of Stokes and Rockingham Counties that is occurring during the warmer months comes from underlain by basalt and sedimentary rocks, which isolated, convective-type storms which arise in the late include sandstone, siltstone, and shale. afternoons and evenings as a result of daytime heating. Downstream from Roanoke Rapids Lake, the Rainfall occurring during cooler months is from more organized frontal storms which cover broad areas of the Roanoke River enters the Coastal Plain where surface region. The higher temperatures and more abundant features are initially dissected and rolling with a moisture in the Coastal Plain reflect the moderating gradual change from well-drained and flat to gently effects exerted by the Atlantic Ocean on the climate in rolling surfaces. In the Coastal Plain, most of the basin that region (Kopec and Clay, 1975). is underlain by unconsolidated materials which date to Since 1900, there have been seven major the Tertiary and Cretaceous ages and are composed of droughts in North Carolina, some of which have alternating layers of sand, silt, and clay. A small resulted in low flows in the Roanoke River Basin segment of the basin, lying along the easternmost (Zembrzuski and others, 1991). The drought of longest fringes of the Coastal Plain near the mouth of the duration affecting streams in the study area occurred Roanoke River, is underlain by sediments dating to the during 1966-71 where low flows having a recurrence Quaternary age and includes layers of sand, silt, interval between 40 and 60 years were observed across and clay.
10 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina 80° 79° 78°
EXPLANATION
STUDY AREA
56 - LINE OF EQUAL AVERAGE ANNUAL TEMPERATURE-lnterval is 2 degrees Fahrenheit - ' DRAINAGE AREA BOUNDARY
36°-
EXPLANATION
STUDYAREA
44- LINE OF EQUAL AVERAGE ANNUAL PRECIPITATION-lnterval is 4 inches DRAINAGE AREA BOUNDARY
35°-
Figure 5. Average annual (A) temperature and (B) precipitation in the Roanoke River Basin, North Carolina and Virginia, 1961-90. Description of Roanoke River Basin 11 80° 79° 78° 37°
VIRGINIA _ NORTH CAROLINA
-. ' \ WARREN ' ^
* PERSON I VANCE/. / HALIFAX y - - GRANVILLE , ' ' I / r~J -' FORSYTH GUILFORD . I 1 ALAMANCE | / f~ % ^ ---'~ I i ORANGE ' »«i 36° i i I DURHAM ' / V <--~';ir / \ ' EDGECOMBE ,"-^'«n *. ,?'?', ^-S*1 \ I ' '' * r i "m i _, ^ , I.MARTIN *S f :j« / 0 10 20 30 40 50 MILES \ ,.> WASHINGTON '
0 10 20 30 40 50 KILOMETERS
EXPLANATION D GRANITE, GRANITIC GNEISS, AND SCHIST (GRANITIC ROCKS) H TERTIARY AND CRETACEOUS SAND, SILT, AND CLAY QUARTERNARY SAND, SILT, AND CLAY D SLATE AND PHYLLITE (SLATE BELT ROCKS) B TRIASSIC SANDSTONE, SILTSTONE, SHALE, AND BASALT (TRIASSIC BASIN ROCKS)
10 20 30 40 50 MILES \
EXPLANATION WELL-DRAINED SOILS MODERATELY WELL-DRAINED SOILS H POORLY-DRAINED SOILS WATER
Figure 6. (A) Geology and (B) generalized soil infiltration groups in the Roanoke River Basin study area, North Carolina.
12 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina The effects of geology on low-flow charac Coastal Plain, the soils of the Norfolk series occupy the teristics cannot be determined solely on the higher percentages of area in those counties within the identification of the geologic unit underneath a given basin. The Norfolk soils consist of sandy loams which area of interest. The geology indirectly affects the are well drained and formed from loamy marine potential for sustained base flow through the soils, or sediments (U.S. Department of Agriculture, 1990). The overburden, into which the underlying rock units are only exception is in Bertie County where soils in the transposed through the processes of physical and Leaf series occupy the highest percentage of all soil chemical weathering. The extent of fractures in the series identified in the survey. Soils in the Leaf series underlying rocks may also be regarded as an indicator are poorly drained and formed from clayey marine of the potential to sustain base flow. Because the sediments (U.S. Department of Agriculture, 1990). fractures act as conduits of water, a rock unit having an Data compiled from Tant and others (1974) abundance of fractures will have a higher degree of indicate that most of the Piedmont Province in the storage capacity than a unit having a smaller number of study area (62 percent) is covered by soils identified as fractures. being moderately well drained (table 3; fig. 6B). Daniel (1989) related well yields to geologic, Exceptions to this include some areas of Caswell and topographic, and well-construction factors using data Person Counties where soils are poorly drained. The from over 6,200 wells drilled in the Blue Ridge, infiltration group and associated minimum infiltration Piedmont, and western edge of the Coastal Plain rate of soil provide an indicator of the water storage physiographic provinces. To establish some indicator within the overburden (Musgrave and Holtan, 1964). of water-bearing potential, Daniel categorized rock Because base flow is defined as sustained flow from units using a classification scheme based on origin, ground water or spring effluent with no surface-runoff composition, and texture. In the Roanoke River Basin component, the streams in the study area covered by study area, there is a high degree of variability of moderately well-drained soils will, assuming all other hydrogeologic units identified by Daniel (1989). factors are equal, have a high potential for Nearly 57 percent of the study area falling within the Piedmont Province is underlain by hydrogeologic units which have average well yields nearly equal to or Table 3. Soil infiltration groups in the Roanoke River Basin study area in North Carolina (compiled from Musgrave and exceeding the overall average yield of 18.2 gal/min Holtan (1964) and Tant and others (1974); adapted from determined by Daniel. Some of the predominant units McMahon and Lloyd (1995)) having average yields that exceed the overall average [mi', square mile. Soil characteristics and minimum infiltration rates for are felsic gneiss (30.1 percent), felsic metaigneous soils falling within one infiltration group are described in table footnotes. Sections of the study area not included are those covered by water bodies (10.6 percent), and schist (8.8 percent). No (approx. 50 mi') and those with unknown soil infiltration groups (approx. comparisons were made for the part of the study area 8 mi2).] within the Coastal Plain because of differences in the ...... Moderately Well drained ... . ' Poorly drained extent of Coastal Plain regions covered by each well drained investigation. However, well yields are generally Soil Area Soil Area Soil Area higher in the Coastal Plain than in the Piedmont and group (mi2) group (mi2) group (mi2)
Blue Ridge Provinces due in part to the greater A 1 156 B 2 1,452 B/D 710 saturated thicknesses of the overburden (C.C. Daniel, B/C 684 C3 111 III, U.S. Geological Survey, oral commun., 1996). Soil surveys conducted by the U.S. Department A/C 15 C/D 178 of Agriculture in the counties lying within the basin D4 139 have resulted in the identification of numerous soil 'Soil Group A - Deep sands, deep loesses, and aggregated soils hav types (U.S. Department of Agriculture, 1910-92). ing minimum infiltration rate of approximately 0.30 to 0.45 inches per hour. Within the Piedmont Province, soils of the Cecil series 2Soil Group B - Shallow loess and sandy loam soils having minimum infiltration rate of approximately 0.15 to 0.30 inches per hour. tend to be the predominant type. These soils are 3SoiI Group C - Clay loams, shallow sandy loams, soils low in characterized as being deep, well-drained, and moder organic matter, and soils high in clay content, and having minimum infiltra ately permeable soils derived from the weathering of tion rate of approximately 0.05 to 0.15 inches per hour. 4Soil Group D - Swelling soils, heavy plastic clays, and certain saline mica gneiss, mica schist, and gneiss (U.S. Department soils having minimum infiltration rate of approximately 0 to 0.05 inches per of Agriculture, 1992). Of the soils identified in the hour.
Description of Roanoke River Basin 13 sustained flow during dry conditions. Streams in the Land use within the Roanoke River Basin in areas covered by poorly drained soils would be North Carolina is mostly rural. Slightly more than expected to have low potential for sustained flows 85 percent of the study area is classified as agricultural during dry periods. As discussed in more detail in later or forest cover (table 4). Four percent of the study area sections, a number of streams in southeastern Caswell is urban with Roanoke Rapids in Halifax County being County and northwestern Person County have little to the largest municipality. Other smaller towns within the no potential for sustained base flows. Other parts of the study area include, from west to east, Danbury in study area covered by poorly drained soils include Stokes County, Wentworth in Rockingham County, most of the Coastal Plain, where swamp conditions are Yanceyville in Caswell County, Roxboro in Person predominant. In all, nearly 33 percent of the study area County, and Williamston in Martin County (plate 1). has poorly drained soils. Well-drained soils in the study Water bodies such as Belews Lake, Hyco Lake and area (5 percent) are found in the eastern and western Afterbay Reservoir, Mayo and Roanoke Rapids Lakes, fringes of the Piedmont and Coastal Plain physio as well as the parts of John H. Kerr Reservoir and Lake graphic provinces, respectively. The existence of well- Gaston within North Carolina account for less than 2 drained soils in this region reflects the transition from percent of the study area. Wetlands occupy nearly 8 the Piedmont to the Coastal Plain Provinces where the percent of the study area and occur in the lower interlocking and abutment of distinct geologic units Roanoke River Basin (hydrologic unit 03010107) in likely results in highly permeable, unconsolidated the Coastal Plain. Within this hydrologic unit, wetlands material in the soil systems. occupy 21 percent of the total area (McMahon and Lloyd, 1995). Land Use Land use in North Carolina has evolved consid erably during the 10 to 15 years since the GIRAS data Land-use information for the study area was base was compiled. McMahon and Lloyd (1995) obtained from the USGS geographic information compared land-use data for several hydrologic units, retrieval and analysis system (GIRAS) (Mitchell and including 03010107, with more recent land-use others, 1977). The GIRAS is the only land-use and information developed from remotely sensed data from land-cover data base in digital format that is available the Landsat Thematic Mapper sensor (Khorram and for all of the United States. Information in the data base others, 1991). They observed several patterns in land- was compiled from aerial photographs taken during the use change in their comparison, the most notable being late-1970's and mid-1980's. For the study area, six increases in agricultural land use accompanied by categories of land use were identified from the data decreases in percentages of forest. This pattern base (table 4). suggests the possibility of forest being converted to Table 4. Areas and percentages of land-use categories in the agricultural uses. In several of the hydrologic units, Roanoke River Basin study area in North Carolina including 03010107, comparisons between percen [mr, square mile. Differences in total drainage area from those listed in tages of urban land use appeared to remain relatively other tables reflect differences in scale of map and accuracy of methods used unchanged while percentages of wetlands were higher by source to compute areas.] in the Landsat data base than in the GIRAS data base. Extent and percentage of study area covered The change in the percentage of wetlands likely reflects Land-use category bV "and-use category1 the methods and resolution of techniques used in (mi2) (percent) compiling the information for each data base and not Urban and developed I4l 40 changes in the percentage of wetlands. Agricultural 1,039 29.7
Forest 1,950 55.7
Water 65 1.9 LOW-FLOW CHARACTERISTICS IN THE
Wetland and swamp 283 8.1 ROANOKE RIVER BASIN
Other (includes rangeland, 25 06 barren land, and areas where Low-flow characteristics were determined for land use i,s unknown) selected gaging stations in the Roanoke River Basin
Totals 3,503 100.0 study area in North Carolina. Historical records of gage height and streamflow from 218 sites in North Carolina 'From U.S. Geological Survey information retrieval and analysis system (GIRAS) and three gaging stations on the Dan and Hyco Rivers
14 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina in Virginia were compiled (plate 1). Streamflow method of analysis for continuous-record sites treated records were examined (table 5, p. 39-53) for selection as partial-record sites is described in subsequent of sites where low-flow characteristics could be discussion below (denoted as C in table 6). determined. Records of discharge collected through the There are a total of seven gaging stations having 1994 water year were used. Of the total 221 sites, 22 daily mean discharge records on the Dan and Smith were continuous-record gaging stations, 191 were Rivers in North Carolina. A common base period, the partial-record gaging stations, and 8 were sites having 1950-93 climatic years (April 1, 1950, through March a combination of continuous- and partial-record 31, 1994), was used to analyze data from sites 4, 50, discharges. The period of record varies from site to site. and 57 and the two long-term continuous-record The low-flow characteristics for selected sites in the gaging stations on the Dan River in Virginia, sites 68 Roanoke River Basin are presented in this section. and 93 (table 6). Flows during this period reflect regulated flow from Philpott Lake in Virginia begin Continuous-record stations ning in August 1950. At site 93 in Virginia on the Dan River, actual data collection began in November 1950. Low-flow characteristics based on continuous Thus, the period of analysis indicated for this site records of discharge were developed for 22 sites. Daily begins with the 1951 climatic year rather than 1950 mean discharges were compiled for 17 of the 22 con (table 6). tinuous-record gaging stations and for 5 of the For the gaging station on the Mayo River, site 38, 8 combined sites that have both continuous- and low-flow characteristics presented in table 6 are based partial-record discharges. Most of these sites were on discharges observed during the climatic years analyzed using frequency curves (Riggs, 1972); a small 1930-70. Because the Mayo River Basin is not affected number required other graphical correlation techniques by any known significant regulation or diversions, low- as explained below. The magnitude and frequency of flow characteristics based on the actual period of low flows for the continuous-record gaging stations are record were assumed to represent a common base shown in table 6. Not all sites having continuous period. To check this assumption, annual minimum records could be used to determine low-flow charac 7-day average discharges were estimated for the teristics. A number of sites on the Roanoke River have 1971-93 climatic years and combined with the only records of gage height or records of discharge observed annual values for the 1950-70 climatic years which are insufficient for use in determining low-flow to develop low-flow characteristics based on the discharge estimates. common base period. Estimates of 7Q10 and 7Q2 Estimates of low-flow discharges for continuous- discharges developed for the extended record record sites having more than 10 years of record were (1950-93) were found to be nearly identical to esti developed by using frequency curves (Riggs, 1972) mates based on the period of actual record (1930-70). (fig. 7). The curves depict the relation between The common base period was not applied to the recurrence interval and the lowest average annual long-term gaging station Roanoke River at Roanoke discharge for a specified number of days at a gaging Rapids (site 181) because additional regulation from station. Frequency curves were developed for annual Roanoke Rapids Lake began in 1965. Additionally, (climatic year) 7-day and 30-day lowest average discharges as well as for the winter (November through records at other gaging stations not having complete March) 7-day lowest average discharge, then fitted record during the common base period were not with the log-Pearson Type III frequency distribution. extended due to the effects of significant regulation at The computed log-Pearson distribution generally the short-term site or due to the occurrence of zero corresponds closely to the distribution of annual low flows. Such factors may not be adequately reflected in flows for sites having long-term periods of record correlation of annual minimum 7-day or 30-day (fig. 7). The method of analysis for these sites is discharges at the short-term station to those at the long- denoted as LP (table 6). For sites 113, 114, and 147, term continuous-record gaging station. which have short-term records of 10 to 15 years, best- Low-flow characteristics developed for the long- fit curves were developed graphically from the Weibull term continuous-record gaging stations using the plots used in the log-Pearson analyses; the method of common base period reflect the effects of regulation analysis for these sites is denoted as G (table 6). The from upstream impoundments. Streamflow in the upper
Low-flow Characteristics in the Roanoke River Basin 15 Table 6. Magnitude and frequency of annual low-flow characteristics at continuous-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina [mi2, square mile; ft3/s, cubic foot per second; PR, continuous-record gaging station having full period of record collected prior to 1950 or having less than 10 years of record of daily mean discharge, treated as a partial-record site where low-flow characteristics were developed using correlation techniques; R, regulated flow; C, estimates based on correlation techniques; LP, estimates based on log-Pearson frequency distribution; U, unregulated flow; <, less than; G, estimates based on best-fit curves developed graphically from the log-Pearson analyses.] Number of to observed Low-flow characteristics .2'(0 6 n '« « 3c7 >. c o> > (5 days of flow E n ^ ll n n 4> 3 >. 0> c £ a>cv^ C « O> '= climatic\ Methodofa TJ 5 c Station name Periodofan S£ 1 C -a % Cn *"E than_essor qualto7Q10 > (?) D 2& V 3si SE 11 |t 4) 1 02068000 Dan River near Asbury, N.C. 71.4 PR 0 18 1.3 23 54 43 44 R C 4 02068500 Dan River near Francisco, N.C. 129 1950-93 0 53 1.4 38 85 68 70 R LP 28 02069000 Dan River at Pine Hall, N.C. 501 PR 0 5 1.3 80 190 165 160 R C
38 02070500 Mayo River near Price, N.C. 242 1930-70 0 67 1.3 65 130 115 110 U LP
50 0207 1000 Dan River near Wentworth, N.C. 1,035 1950-93 0 83 1.2 175 415 360 340 R LF
56 0207 1 500 Dan River at Eden, N.C . 1,133 PR 0 33 1.1 190 440 375 360 R C 57 02074000 Smith River at Eden, N.C. 538 1950-93 0 765 1.2 175 290 215 250 R LP
64 02074218 Dan River near Mayfield, N.C. 1,760 PR 0 7 1.2 375 750 650 640 R C 68 02075000 Dan River at Danville, Va. 2,050 1950-93 0 102 1.1 425 810 700 685 R LP
75 02075160 Moon Creek near Yanceyville, N.C. 32.8 1962-73 0 24 0.8 0.4 3.0 3.0 1.5 U LP
93 02075500 Dan River at Paces, Va. 2,550 1951-93 0 98 1.1 460 920 810 750 R LP 97 02077200 Hyco Creek near Leasburg, N.C. 45.9 1965-93 456 456 1.0 0 0.5 1.8 0.2 U LP 111 02077230 South Hyco Creek near Hesters 31.7 PR 15 15 0.9 0 1.4 0.8 0.5 U C Store, N.C.
113 02077240 Double Creek near Roseville, N.C. 7.47 1965-74, 10 58 1.0 <0.1 0.6 0.6 0.5 U G 1977-81
114 02077250 South Hyco Creek near Roseville, 56.5 1967-77 98 98 1.1 0 2.5 1.5 1.0 U G N.C.
131 02077300 Hyco River at McGehees Mill, 198 PR 0 27 0.7 3.0 9.2 3.8 7.0 R G N.C. 1
132 02077303 Hyco River below Afterbay dam 202 1974-86, 0 64 0.9 2.4 12.8 6.1 10.0 R LP near McGehees Mill, N.C. 1989-93
140 02077500 Hyco River near Denniston, Va. 289 1974-93 0 45 0.9 10.4 24.9 18.0 21.0 R LP 147 02077670 Mayo Creek near Bethel Hill, N.C. 53.5 1984-94 0 6 0.7 1.0 2.9 2.0 2.5 R G 181 02080500 Roanoke River at Roanoke Rapids, 8,384 1964-93 0 177 1.0 1,100 2,400 1,100 1,800 R LP N.C.
194 02081000 Roanoke River near Scotland 8,671 PR 0 12 0.8 1,120 2,500 1,120 1,880 R C Neck, N.C.
2 1 2 0208 111310 Cashie River near Windsor, N.C. 108 PR 211 211 1.0 0 1.5 0.2 0.2 U G
Site now inundated by impoundment. Low-flow characteristics represent regulated flow from Hyco Lake.
16 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina 1,000
ANNUAL MINIMUM 7-DAY AVERAGE DISCHARGE III o LOG-PEARSON TYPE III CC < FREQUENCY CURVE O CO fri O < LiJ
= O
10 1.005 1.02 1.05 1.1 1.25 1.5 2 3 5 10 20 50 100 200 RECURRANCE INTERVAL, IN YEARS
Figure 7. Low-flow frequency curve of annual minimum 7-day discharges using log-Pearson Type frequency distribution at Mayo River near Price, N.C. (site 38; plate 1).
reaches of the Dan River has been regulated by Talbott which is 40 percent of the basin at the gaging station at and Townes Reservoirs (drainage areas of 20.2 mi"^ and Smith River at Eden (site 57). However, just down 32.9 mi",^ respectively) in Virginia since 1938. The stream from the confluence of the Dan and Smith drainage basin upstream from Townes Reservoir is Rivers where the drainage area is nearly 1,680 mi2, less 26 percent of the basin at Dan River near Francisco than 15 percent of the total basin is upstream from (site 4; 129 mi2) and 7 percent of the basin at Dan River Townes Reservoir and Philpott Lake. Table 6 indicates at Pine Hall (site 28; 501 mi2). Thus, the effects of for each site whether flows are regulated (R) or unreg regulation on the Dan River, while significant in the ulated (LO by upstream impoundments. Low-flow upper reaches, rapidly diminish as the drainage area characteristics for the regulated sites can be considered increases. The effects of regulation on streamflow in valid as long as the current pattern of regulation the Dan River become more significant at the continues to exist. confluence of the Dan and Smith Rivers. Philpott Lake Eight continuous-record sites having less than in Virginia drains 216 mi2 of the Smith River Basin, 10 years of record or with full periods of record
Low-flow Characteristics in the Roanoke River Basin 17 collected prior to 1950 were treated as partial-record the partial-record and index sites as well as similarity stations for the analyses of low-flow characteristics. in some basin characteristics such as drainage area and Daily mean discharges at these sites were correlated topography. with concurrent flows at nearby long-term continuous- Defining the relation between concurrent flows record gaging stations where low-flow characteristics is usually based on either statistical techniques or had been developed. Correlations at sites 28, 64, and graphical interpretation whereby visually-fitted lines 111 having less than 10 years record provided a strong are drawn among the concurrent flows (Riggs, 1972). relation for determining low-flow characteristics. In this investigation, graphical interpretation was used Streamflow data for sites 1 and 56 on the Dan River and to establish the relation between the concurrent flows. site 194 on the Roanoke River were collected entirely Ordinary least squares regression techniques were or almost entirely before 1950. Low-flow character applied to a small number of sites; however, the istics at these sites were determined by correlating, for nonlinear relation exhibited in many of the correlations the period of record, daily mean discharges with flows indicated that visually-fit lines would more adequately at nearby long-term continuous-record gaging stations. For these six sites, the method of analysis is denoted by describe the relations between concurrent flows. C (table 6). At most partial-record sites, correlations of the At sites 131 and 212, having less than 10 years of discharge measurements with concurrent flows at record, correlations with concurrent flows at nearby multiple index sites yielded several relations from long-term continuous-record gaging stations were poor which estimates of low-flow discharges could be and did not provide a relation from which low-flow determined. From each relation, estimates of low-flow characteristics could be determined. Thus, low-flow discharges were derived from the individual characteristics were derived from graphical interpre correlation plot. Thus, to determine overall estimates of tation of the Weibull probability plots used in the log- low-flow discharges (7Q10, 30Q2, W7Q10, and 7Q2) Pearson frequency analyses using available record. for each partial-record station, individual estimates Because this approach is the same as that used for sites derived from each correlation were averaged. How having 10 to 15 years of record where best-fit curves ever, individually derived estimates from poor were developed graphically, the method of analysis for correlations where visually-fit lines could not be sites 131 and 212 also is denoted by G. established or otherwise were deemed suspect were not included in the average for overall estimates. Low-flow characteristics for the partial-record Partial-record stations sites reflect unregulated conditions with the exception Using the techniques discussed by Riggs (1972), of two sites (table 7). Low-flow discharges shown for low-flow characteristics were determined for 58 of the sites 80 and 195 on the Dan and Roanoke Rivers, 191 sites in the Roanoke River Basin study area respectively, reflect regulated conditions from up identified as having partial-record data and for 2 of the stream impoundments (table 7). Thus, estimates for 8 combined sites that have both continuous- and these two sites can only be considered valid as long as partial-record discharges (table 7, p. 54-56). Sites the pattern of regulation observed during the years in having 10 or more discharge measurements were which discharge measurements were obtained included in the analyses of low-flow characteristics, as continues to exist. well as sites where low-flow characteristics have been previously published or for which knowledge of low- flow discharges were necessary in the development of Occurrence of zero or minimal 7Q10 discharge profiles. discharge Discharge measurements of base flow at the partial-record stations were correlated with concurrent Estimated 7Q10 discharges at 30 of the 82 sites flows at nearby index sites, typically continuous-record were determined to be zero (tables 6, 7). However, gaging stations where low-flow characteristics had when arranged in order of ascending drainage area, been determined (fig. 8). Index sites for possible use in there was no clear indication of a maximum drainage the correlation analysis of concurrent flows were area below which 7Q10 discharges are generally zero. selected using several factors including proximity of In addition to the sites having zero 7Q10 discharge,
18 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina CT 3 O P O fD 5. r> 3 ?T 3. 3" S g 0 C £ 3 S O fs x I fD 3 -I 3 ^ c/2 p P ^r- oTJ2- o 3 Us- oomil h_|_ HI-; ^ 3 fD
20 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Belews, Hyco, and Mayo Creeks, and the Roanoke minimum release is as follows: 2,000 ft /s during the River (at Roanoke Rapids). The effect of required months of May through September; 1,500 ft3/s during minimum flow releases from these impoundments the months of April and October; and 1,000 ft3/s in the varies from site to site. Low-flow characteristics at months of November through March. The regulated- ungaged sites downstream from an impoundment are flow 7Q10 discharge at the continuous-record gaging determined as the product of the estimated pre- station downstream from Roanoke Rapids Lake impoundment low flows and the drainage area between (site 181; table 6) is 1,100 ft3/s and is based on the daily the dam and site of interest plus the minimum flow mean discharges observed during the 1964-93 climatic from the impoundment. Discharge profiles presented in years. While the minimum flow release from Roanoke this report for the Hyco and Roanoke Rivers include Rapids Lake is less than the 7Q10 discharge during the regulated low flows downstream from impoundments. winter months (November through March), the mini The low-flow characteristics determined for these mum flow releases during the warm-season months of reaches are based on records from the long-term April through September exceed the 7Q10 discharge. continuous-record gaging stations (sites 132, 181) immediately downstream from each impoundment (table 6). Town Fork Creek At Belews Creek, the impoundment is located Town Fork Creek drains 135 mi o in portions of about one-half mi upstream from the mouth where Stokes and Forsyth Counties in the westernmost part of streamflow empties into the Dan River. Belews Creek 'j the study area. The largest tributaries draining to Town drains nearly 73 mi of the study area; the impound Fork Creek are Buffalo (different from the Buffalo ment retains flow from about 70 mi2 or 96 percent of Creek of Rockingham County profiled in this report), the Belews Creek Basin. Thus, streamflow observed at Neatman, and Old Field Creeks (fig. 9A). Estimates of the mouth consists mostly of the flow being released low-flow discharges shown on the profiles were based from the dam. No minimum flow is required by permit; on the unit flows at the three partial-record stations in however, minimal flow rates observed in operations of 'j the basin (table 7); the 7Q10 discharge at the mouth is the impoundment are nearly 150 ft /s (Ken Broughton, nearly 11 ft3/s (fig. 9B). The potential for sustaining Duke Power, 1996). Hyco Lake drains 202 mi2 base flow in the Town Fork Creek Basin is high. Giese (site 132) of the Hyco River Basin which, at its mouth ^\ and Mason (1993) also identified this part of North in Virginia, is about 425 mi in size. Nearby, Mayo Carolina as having a high potential to sustain base Lake drains about 54 mi2 of the nearly 62 mi2 Mayo flows. Twenty-one NPDES permits are recorded for the Creek Basin. Permit-required minimum flow rates Town Fork Creek Basin. Permitted flows for the downstream from the Hyco and Mayo impoundments o o 11 NPDES discharges (including two into Town Fork are 10 ft /s and 2 ft /s, respectively (Marshall Creek) which must comply with wastewater-treatment Lundsford and Mark Frederick, Carolina Power and standards compose nearly 9 percent of the 7Q10 Light, 1996). Analyses of the post-impoundment discharge at the mouth. On September 24, 1959, and record at the continuous-record gaging stations August 14, 1963, flows in the basin appear to have been immediately downstream from the Hyco and Mayo at or somewhat higher than 30Q2 discharge conditions. dams reveal the low-flow 7Q10 discharges, 2.4 ft3/s o and 1.0 ft /s (sites 132, 147; table 6), respectively, to be less than the minimum flow releases. Hogans Creek The largest impoundment in the study area is on ^\ the Roanoke River at Roanoke Rapids Lake. Hogans Creek drains over 24 mi of Rocking Immediately upstream from the lake are two much ham County southwest of Madison; its largest tributary larger impoundments, Lake Gaston and John H. Ken- is Little Hogans Creek (fig. 10A). Low-flow discharges Reservoir in Virginia. Consequently, the segment of the for the entire reach were estimated using the unit low Roanoke River between Roanoke Rapids and its mouth flows for the partial-record station (site 47) on Hogans is one of the most heavily regulated rivers in North Creek just above the mouth. The 7Q10 discharge at the Carolina. The Federal Energy Regulatory Agency mouth is 1.3 ft3/s (fig. 10B). Total permitted flow for license for Roanoke Rapids Lake specifies a minimum the three known NPDES discharges in the basin is release which varies by season (Fransen, 1991). The nearly 10 percent of the 7Q10 discharge at the mouth.
Discharge Profiles for Selected Streams in the Roanoke River Basin 21 140
130
120
110
100
CO LLJ I 90 trLU ^ 80 O CO - 70 <
60 111 O < 1 50 tr Q 40
30
20
10
0
36
34
32
30
28
Q 26 O a 24 CO OC oo HI " Q. t 20 Ll_ I 18
16
O 14 oc 12
10
26 24 22 20 18 16 14 12 10 8 RIVER MILES (ZERO MILE AT MOUTH OF TOWN FORK CREEK)
Figure 9. Relation of river miles to (A) drainage area and (B) low-flow discharge for Town Fork Creek.
22 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina 26
24
22
20
18
16
I 14 12
O < 10
0
8.5
80
7.5
7.0
6.5 ie.o O o UJ c c C/3 0-0 CC UJ o- 5.0
UJ UJ .. ,- U- 4.5 O CO g4.0
5-3.5 O < 3.0 O D- ^-O25
2.0
1.5
1.0
0.5
0 13 12 10 987654 RIVER MILES (ZERO MILE AT MOUTH OF HOGANS CREEK)
Figure 10. Relation of river miles to (A) drainage area and (B) low-flow discharge for Hogans Creek.
Discharge Profiles for Selected Streams in the Roanoke River Basin 23 Buffalo Creek flows which are among the highest in the study area. The uppermost reaches of the basins drained by the two Buffalo Creek drains nearly 22 mi ^ of Rocking- rivers have high annual precipitation compared with ham County just west of Eden; the largest tributary is long-term averages of annual precipitation observed in Buffalo Creek Branch (fig. 11 A). Miscellaneous other parts of the study area (fig. 5B). Additionally, a measurements of discharge have been made at four transition in the underlying geology from the Blue sites in the Buffalo Creek Basin. However, none of the Ridge to the Piedmont physiographic province most sites has a sufficient number of measurements for likely results in a high degree of fissures and rock which concurrent discharges at nearby index stations openings which, in turn, results in higher availability of are available for correlation analysis. Thus, estimates water storage in surficial aquifers. Steep stream of low flow discharges shown on the profiles are based gradients in the upper ends of the Mayo and Smith primarily on average unit flows from three nearby River Basins also likely contribute to the high unit low partial-record stations (sites 47, 49, 51) which drain flows. The 7Q10 discharges at the mouths of the Mayo basins similar in size and characteristics to Buffalo and Smith Rivers are 80 ft3/s and 178 ft3/s, respectively Creek. Although low-flow discharges shown on the (fig. 13A and B). Permitted flows from known NPDES profile for Buffalo Creek are considered ungaged permits in North Carolina for discharges into the Mayo estimates, favorable comparison of the unit low flows River account for less than 3 percent of the estimated at the three nearby sites provides a basis upon which 7Q10 discharge at the mouth. No significant NPDES estimates can be determined for ungaged sites in the discharges exceeding 1 Mgal/d (1.5 ft /s) are known to immediate vicinity. The estimate of 7Q10 discharge at exist on the reach of Smith River within North the mouth is 1.1 ft3/s (fig. 11B). Twelve NPDES Carolina. permits have been assigned to facilities which discharge into streams in the Buffalo Creek Basin. Total permitted flow from the three facilities which Country Line Creek must comply with wastewater-treatment standards is less than 3 percent of the 7Q10 discharge at the mouth The Country Line Creek Basin drains 140 mi2 in of Buffalo Creek. Actual discharge measurements much of central Caswell County. The largest tributary obtained at points along Buffalo Creek on August 14, is South Country Line Creek (fig. 14A). This part of the 1963, indicate that flows were near 7Q10 discharge study area represents a region of rapid transition in conditions (fig. 11B). potential to sustain base flow. In the western part of the Country Line Creek Basin, the potential to sustain flow Mayo River and Smith River is moderate but becomes very low in the eastern part of the basin. Two factors exist which may partially Low-flow discharge profiles were developed for account for the reduction in base-flow potential. First, Mayo and Smith Rivers, the two largest tributaries of the basin contains soils having moderate to poor infil the Dan River in Rockingham County. At the mouths, tration rates (fig. 6B). Because low flow is sustained the drainage areas of the Mayo and Smith Rivers are base flow that, in turn, is derived from ground water 297 mi2 and 546 mi2, respectively (fig. 12A and B). stored in the surficial aquifers, soils having low Much of the basins drained by each river lie in Virginia, infiltrations rates will not have water stored for later and the rivers travel a short distance in North Carolina release during extended dry periods. Second, irrigation before emptying into the Dan River. The Mayo River is withdrawals also occur in Caswell County. Water-use not known to be affected by any regulation or signif records compiled in 1990 for the county indicate that icant upstream diversions. However, the Smith River an average of over 1.4 Mgal/d (2.2 ft3/s) in irrigation has been regulated by Philpott Lake in Virginia since withdrawals are made for agricultural purposes. 1950, the starting year of the common base period Profiles of actual measurements made at a number of (1950-93 climatic years) chosen for the analysis of sites on July 19, 1966, and September 10, 1968, reveal long-term continuous-record gaging stations in the Dan a loss of water in the lower reaches of Country Line River Basin. Creek. No specific information is available to attribute The Mayo and Smith Rivers near the State line the loss of water on these dates to irrigation; however, between North Carolina and Virginia have unit low irrigation withdrawals are known to have occurred in
24 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina DISCHARGE, IN CUBIC FEET PER SECOND DRAINAGE AREA, IN SQUARE MILES CD C
N . Buffalo Creek at Secondary Road 1515 near I Buffalo Creek at Secondary Road 1515 near Sunset Hills, N.C. (USGS 0207103295) Sunset Hills, N.C. (USGS 0207103295) DO cp_ o'S-
o
Buffalo Creek above Eden, N.C. (Site 52) Buffalo Creek above Eden, N.C. (Site 52)
CD w o b Buffalo Creek branch - Buffalo Creek Branch 5 m Q. 92. 0) CQ CD
CD 0) Buffalo Creek tributary i Buffalo Creek tributary 0) Q. 3 5"
Buffalo Creek near Eden, N.C. > ro (Site 54) 5 b Buffalo Creek near Eden, N.C. (Site 54) t o JJ m m ro CQ Buffalo Creek tributary ' CD
03
I - Buffalo Creek near O Buffalo Creek near Stoneville, N.C. (Site 55) O Stoneville, N.C. (Site 55) CD CD 7?
Buffalo Creek at mouth at Eden, N.C Buffalo Creek at mouth at Eden, N.C. (USGS 0207111350) - (USGS 0207111350) 300
295
290
285
280 w LU ^275 rrLU zl 270 O
§265 LU
< 260
1 1 255 rr Q 250
245
240
235
230 16 15 14 13 12 11 10 9 8 7 65 RIVER MILES (ZERO MILE AT MOUTH OF MAYO RIVER) 547
546
545
544 rr 543 z> O w -. 542 iS tr < 541
540
539
538
537 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 RIVER MILES (ZERO MILE AT MOUTH OF SMITH RIVER)
Figure 12. Relation of river miles to drainage area for (A) the Mayo River and (B) the Smith River.
26 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina 170
160 -
15 14 13 12 11 10 9 8 7 6 5 RIVER MILES (ZERO MILE AT MOUTH OF MAYO RIVER) 300
290
280
270 g 260 W7Q10 O LU w CC 250
230
7Q2 220
a eg 200 CO Q) o> co o> 15 ° .> j- M 190 DC ^ 0
7Q10 180
170 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 RIVER MILES (ZERO MILE AT MOUTH OF SMITH RIVER)
Figure 13. Relation of river miles to low-flow discharge for (A) the Mayo River and (B) the Smith River.
Discharge Profiles for Selected Streams in the Roanoke River Basin 27 150
140
130
120
110
15 O 100
90
80
70
60
50
40
30
20 £- i 10
0
7.5
30Q2 7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
LU3.0
I 25 O
2.0
Dashed line indicates uncertainty in changes 1.5 5 ± in 7Q10 low-flow discharge between site 91 and mouth of Country Line Creek. The 7Q10 1.0 of 0.7 ft /s at site 91 is extended to mouth -
0.5
40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 RIVER MILES (ZERO MILE AT MOUTH OF COUNTRY LINE CREEK)
Figure 14. Relation of river miles to (A) drainage area and (B) low-flow discharge for Country Line Creek.
28 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina the Country Line Creek Basin. Given the size of the County and has the largest percentage of urban and basin and its location in central Caswell County, it is developed land use among the streams profiled during likely that a significant percentage of the irrigation this investigation (fig. 16A). Additionally, flows in the withdrawals are from Country Line Creek. The loss of lower reaches of Marlowe Creek consist mostly of water is also reflected in the decrease in 7Q10 treated effluent released by a local municipal waste- discharge between South Country Line Creek and water-treatment plant. Just upstream from the mouth, site 91 shown on the profile (fig. 14B). At least three the 7Q10 discharge is 0.2 ft3/s (site 137) under what NPDES permits are present in the basin, all of which would be considered natural-flow conditions. The must comply with wastewater-treatment standards. permitted flow specified by the NPDES permit for The total permitted flow from the three discharges is release of the treated effluent is 5 Mgal/d, or nearly o nearly 60 percent of the 7Q10 discharge at the mouth 7.7 ft /s. The average flow released into Marlowe o (0.7 ft3/s) of County Line Creek (fig. 14B). The high Creek is approximately 2.9 Mgal/d, or about 5 ft /s percentage reflects lo\ potential of base flow, (table 2) which is reflected on the profile (fig. 16B). particularly in the lower reaches of the basin.
Hyco River Dan River Profiles developed for Hyco River show Profiles developed for the Dan River present the drainage areas and low-flow discharges from the drainage areas and low-flow discharges for the reach of headwaters (where it is known as Hyco Creek) to the the river within North Carolina (fig. 15A and B). gaging station on Hyco River near Denniston, Virginia Continuous- and partial-records of discharge are (site 140) (fig. 17A and B). The most prominent feature available at nine gaging stations (including two in of the discharge profiles is the effect of Hyco Lake and Virginia); low-flow estimates developed at these Afterbay Reservoir on downstream flows. Hyco Lake locations serve as the anchor points on the discharge is the largest of the two impoundments; however, profile. Unit low flows for the uppermost gaging station downstream flows are regulated by Afterbay Reservoir, (site 1; table 6) reveal high potential to sustain base which is located immediately downstream from the flow, similar to the high-unit low flows on the Mayo dam on Hyco Lake. At the State line, Hyco River drains and Smith Rivers. Just downstream from Town Fork 277 mi2 of Caswell and Person Counties, 202 mi2 of Creek in Stokes County, unit low flows are approxi which is drained by the impoundment. Not including mately 50 percent of the unit low flows further those which drain directly into the lake, the largest upstream in the basin; unit flows remain fairly constant tributary to Hyco River is Storys Creek, including the as the Dan River continues its downstream course Marlowe Creek Basin. Upstream from the through North Carolina and into Virginia. A number of impoundment, low-flow discharges developed at the NPDES permits exist for discharges from municipal continuous- and partial-record gaging stations indicate and utility facilities into the Dan River. The NPDES that the potential to sustain base flow is extremely low. permit having the largest permitted flow is for a Estimates of zero 7Q10 discharges are numerous for discharge of about 70 Mgal/d (110 ft3/s) from a utility streams in this area; unit flows for the remaining low- company. However, the same amount of flow is flow statistics shown on the profiles also reflect the low withdrawn just upstream from the discharge point potential to sustain base flow. The Hyco Creek Basin resulting in no net loss in flow. The sum of the (upstream from Hyco Lake) is underlain by soils remaining permitted flows for known discharges into similar to those found in the adjacent Country Line the Dan River is nearly 7 percent of the 7Q10 discharge Creek Basin; these soils have low infiltration rates at the gaging station on the Dan River at the State line (fig. 6B). Downstream from the dam on Afterbay (site 64) downstream from Eden (near May field). Reservoir, low flows are affected by the flows released from the lake. A very large withdrawal exceeding 1,100 Mgal/d is made by the utility company that owns Marlowe Creek the lake; however, nearly the same volume is returned to the lake. No other withdrawals and return discharges Similar in size to the Buffalo Creek Basin, the in North Carolina are known to exist for the reach of r\ Marlowe Creek Basin drains nearly 22 mi of Person Hyco River profiled in this report.
Discharge Profiles for Selected Streams in the Roanoke River Basin 29 2,600
2,400
2,200
2,000 to 1 >800 LLJ uj 1,600 cc < §> 1-400
1,200
< 1,000
800
600
400
200
0
1,000
900
800
g700 o
600
500
LU400 CC o gsoo
200
100
170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 RIVER MILES (ZERO MILE AT MOUTH OF THE DAN RIVER)
Figure 15. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Dan River.
30 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina 22
20
18
16
14
10
o < ? 8
30Q2
7Q10
CC £
^ «
543 RIVER MILES (ZERO MILE AT MOUTH OF MARLOWE CREEK)
Figure 16. Relation of river miles to (A) drainage area and (B) low-flow discharge for Marlowe Creek.
Discharge Profiles for Selected Streams in the Roanoke River Basin 31 Hyco Lake and Afterbay Reservoir
Hyco Lake and Afterbay Reservoir
45 40 35 30 25 20 15 10 RIVER MILES (ZERO MILE AT MOUTH OF HYCO RIVER)
Figure 17. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Hyco River.
32 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Roanoke River characteristics cannot be reliably estimated for the Roanoke River at its mouth due to lack of streamflow Drainage area and low-flow discharge profiles data and unknown effects of tides, the percentage of for the reach of the Roanoke River between Roanoke permitted flows to the 7Q10 discharge is unknown. Rapids Lake and the mouth show the effects of the However, the ratio of permitted flows in the entire river narrow basin shape and regulation. The basin between to the 7Q10 discharge at the gaging station at Roanoke Roanoke Rapids Lake and the mouth is very narrow Rapids (site 181) is about 18 percent. The percentage and varies in width from about 8 mi in the reaches can be regarded as a reliable estimate of the maximum downstream from the lake to about 25 mi in the vicinity percentage expected at the mouth, because the 7Q10 of Williamston. The drainage-area profile reflects the discharge is not likely to be much higher than the narrow basin shape by the small increases in drainage 1,100 ft3/s at site 181. While low-flow estimates on the area contributed by tributaries. The larger tributaries to Roanoke River would be expected to increase in the the Roanoke occur in the lower reaches of the basin and downstream direction, the existence of zero or minimal include Conoho and Welch Creeks; the largest are 7Q10 discharge contributions from tributaries plus the Cashie and Middle Rivers which merge with the unknown effects from tides would limit the magnitude Roanoke River at its mouth (fig. ISA). of flow increases. The discharge profile depicts low flows for the reach of the river between the gaging stations at Roanoke Rapids (site 181) and at Williamston (site 200) (fig. 18B). Average unit low flows for the SUMMARY regulated period for the gaging stations near Roanoke This report describes low-flow characteristics Rapids and Scotland Neck (sites 181, 194) were for the Roanoke River Basin in North Carolina through applied to the entire reach shown on the profile. The the 1994 water year and 1993 climatic year. Low-flow same average unit low flows also were applied to the characteristics were summarized for a number of sites near Oak City and at Williamston (sites 195, 200) existing gaging stations in the study area, and drainage in order to extend the profile. area and low-flow discharge profiles were developed Streamflow records for locations downstream for selected rivers and streams. Estimates of low flows from the gaging station near Oak City are either presented in this report were prepared in cooperation insufficient or unreliable for use in developing with the North Carolina Division of Environmental estimates of low flows. Additionally, much of the lower reaches is affected by tides from the Albemarle Sound, Management (DEM) of the Department of Health, making any attempts at estimation subject to large Environment, and Natural Resources. In 1991, the errors. The discharge profiles depict a river with flows DEM began using a basinwide approach in its during extended dry conditions composed largely of assessment of water-quality conditions in North releases from Roanoke Rapids Lake. The unit low Carolina; part of the assessment includes the simul flows for partial-record stations on tributaries in the taneous evaluation of National Pollution Discharge vicinity of Roanoke Rapids show low to moderate Elimination System (NPDES) permits for point-source potential for sustaining base flow. The transition of discharges into streams within the basin. The Roanoke underlying geology from Piedmont to Coastal Plain River Basin in North Carolina is one of 17 major river physiographic-province terrain likely results in a soil basins selected by the DEM for the purposes of conducting the basinwide assessments. overburden that has infiltration rates sufficient to allow i-y storage of water in surficial aquifers. In the lower About 9,700 mi in size, the Roanoke River reaches of the basin, the potential for sustained base Basin is located in parts of Virginia and North Carolina. flow decreases significantly. Giese and Mason (1993) Nearly 36 percent of the basin lies in North Carolina also described the Coastal Plain region as an area and is drained by the Dan and Roanoke Rivers. The having low potential to sustain base flow. western two-thirds of the study area, drained by the Six NPDES permits exist for facilities which Dan River, is in the Blue Ridge and Piedmont physio must comply with wastewater-treatment standards graphic provinces and is characterized by rolling and before discharging into the river. The largest permitted hilly topography. The Dan River flows into the discharge is for nearly 83 Mgal/d (128 ft3/s) into the Roanoke River in Virginia. The eastern one-third of the Roanoke River near Plymouth. Because low-flow basin, drained by the Roanoke River, is in the Coastal
Summary 33 2,800
2,600 30Q2
2,400
£ 2,200 t3 LU LJ_ ^ 2,000
O
1,800
O 2 1,600
1,400
1,200
1,000 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 RIVER MILES (ZERO MILE AT MOUTH OF ROANOKE RIVER)
Figure 18. Relation of river miles to (A) drainage area and (B) low-flow discharge for the Roanoke River.
34 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Plain physiographic province, characterized by a basin, although some of the high unit flows are gradual transition from gentle, rolling hills with little attributed to the effects of upstream regulation. relief to nearly level land surfaces. Available documentation of soils was examined Selected basin characteristics and their known to determine the effects on low flows in the study area. effects on the low-flow characteristics are described in Soil infiltration groups, when mapped throughout the this report. An accounting of the flow modifications study area, correspond to the potential to sustain base caused by impoundments and diversions from and into flows. In eastern Caswell County and western Person streams in the study area was made to determine the County, the presence of soils classified as having low effects on low-flow characteristics. Nearly 360 im infiltration rates are reflected in the low potential to poundments having dams with structural heights sustain base flows for streams in this area. The Country exceeding 15 ft were identified in the investigation. Line Creek Basin occupies this area; a number of sites Four are major impoundments: Belews Lake, Hyco in the lower half of the basin have zero or minimal Lake and Afterbay Reservoir, Mayo Lake, and 7Q10 discharges (defined as less than 0.1 ft3/s). Many Roanoke Rapids Lake. These impoundments affect low soils in the study area within the Coastal Plain are also flows through the minimum releases maintained at classified as having low infiltration rates. Similarly, the each impoundment. potential for sustaining base flows at many of the A total of 24 withdrawals exceeding Mgal/d are gaging stations in this area is low. registered with the State of North Carolina; most are Land use in the basin is mostly rural; over made by municipalities and major industries for water 85 percent is classified as agricultural or forest cover. supply and manufacturing purposes. The State also Four percent is urban with Roanoke Rapids being the permits 366 point-source discharges under the NPDES largest municipality in the study area. Data describing permitting system; 17 are deemed by the State as being land use in the study area indicates that percentages for major discharges. Many of the major withdrawals and most categories have remained relatively unchanged return discharges can be paired resulting in negligible since the mid-1970's. Examination of recent land-use effects on low flows. Flow modifications having the data indicates exceptions to this in areas where most significant effects on low flows are likely those agricultural land use has increased while forested land unknown withdrawals in small to mid-size basins use has decreased. This suggests the possibility that which are not required to be registered with the State. changes in these categories are related. That is, forested Often made for irrigation purposes, the cumulative areas are being converted to areas for agricultural use. effect of multiple withdrawals, particularly in basins The effects of land use on low flows in the study area having low potential to sustain base flows, would be to are likely insignificant. further reduce the availability of flow for assimilating Records of surface-water data were identified effluent from point-source discharges. In this report, and compiled for 218 sites in the study area and three low flows in the Country Line Creek Basin were sites on the Dan and Hyco Rivers in Virginia. Low-flow determined to be partly affected by irrigation with characteristics (7Q10, 30Q2, W7Q10, and 7Q2) were drawals known to occur, but in unknown specific determined for 82 sites (22 continuous-record and amounts. 60 partial-record). For seven gaging stations having The variability of average rainfall amounts continuous records of daily mean discharge on the Dan occurring in the Roanoke River Basin is partly and Smith Rivers, a common base period (1950-93 cli reflected in the potential to sustain low flows in the matic years) was selected for use in determining low- study area. Higher rainfall amounts in the mountain flow characteristics. When unit low flows were plotted and foothills regions of Virginia correspond to higher on a map of the study area, two general areas of zero or unit low flows at gaging stations in the western portions minimal 7Q10 discharges were recognized. A number of the study area. Flows at the long-term continuous- of sites in eastern Caswell County and western Person record gaging station at Mayo River near Price (site 38) County have zero or minimal 7Q10 discharges^ as well have high potential to sustain base flows. Similarly, as many of the sites in lower portions of the Coastal flows observed at long-term gaging stations on the Dan Plain. This poorly sustained base flow is reflective of and Smith Rivers have high unit low flows attributable soils having low infiltration rates; very little water is to the higher rainfall amounts which occur within the stored in the surficial aquifers in these areas which
Summary 35 results in little to no water being available for release to The Mayo and Smith Rivers drain 297 mi" and streams during extended dry conditions. 546 mi2, respectively. Much of the basin drained by Drainage area and low-flow discharge profiles each river lies in the mountains and foothills regions of were developed for 10 streams and rivers in the study Virginia, where average rainfall amounts in combi area. Streams profiled in this report include the two nation with significant slopes in topography yield some mainstems, the Dan and Roanoke Rivers, along with of the highest unit low flows determined in the investi selected tributaries to the Dan River. The selected gation. The Mayo River is unaffected by regulation, tributaries include Town Fork Creek, Hogans Creek, while the Smith River is affected by regulation from Mayo River, Buffalo Creek, Smith River, Country Line Philpott Lake in Virginia. On the Mayo River, the Creek, Marlowe Creek, and Hyco River. Drainage-area percentage of permitted flows (in North Carolina) to profiles show increases in the basin size for reaches of the 7Q10 discharge at the mouth is less than 3 percent. the streams in North Carolina. The low-flow discharge profiles depict the 7Q10, 30Q2, W7Q10, and 7Q2 No known point-source discharges exist on the brief discharges. For a few streams, a profile of actual stretch of the Smith River in North Carolina prior to its convergence with the Dan River. measurements obtained at multiple points on Septem >-\ ber 24, 1959; August 14, 1963; July 19, 1966; and The Dan River drains nearly 3,900 mi of September 10, 1968, provide a "snapshot" of actual Virginia and North Carolina which includes 1,630 mi"9 flow conditions on these dates. For each stream, the of the study area. Profiles for the river were limited to percentage of total known permitted NPDES flows to a 130-mi reach between the continuous-record gaging 7Q10 discharge at the mouth or other identified stations at the State line (site 1) and near Paces, location was determined. Virginia (site 93). Unit low flows for the Dan River Hogans, Buffalo, and Marlowe Creeks each vary along the stretch of the river profiled in this report, drain basins less than 25 mi2. The percentages of with the highest values being reported in the uppermost permitted flows to 7Q10 discharges at the mouths of reaches in Stokes County. The major withdrawals and Hogans and Buffalo Creeks are 10 and 3 percent, point-source discharges do not have any significant respectively. At Marlowe Creek, the 7Q10 discharges effect on the Dan River; most withdrawals and are composed mostly of point-source discharges discharges for a given facility occur within a short upstream from site 137. Under what would be considered "natural-flow" conditions, the 7Q10 distance resulting in negligible losses of flow. The discharge at this site is 0.2 ft3/s (table 7). However, the percentage of known permitted flows to the 7Q10 average flow from the point-source discharge is nearly discharge at the gaging station near Mayfield (site 64) 5 ft /s. The low-flow discharge profile shown for is nearly 7 percent. Marlowe Creek reflects the presence of the point- Drainage area and low-flow profiles for the source discharge. Roanoke River were limited to the reach of the river Town Fork and Country Line Creeks each drain downstream from Roanoke Rapids Lake. Flow in the nearly 140 mi2 of the study area. The percentages of Roanoke River is heavily regulated by a series of lakes permitted flows to 7Q10 discharges are 9 and 60 per which occur along the North Carolina-Virginia State cent, respectively. Eleven point-source discharges line. The drainage-area profile reflects the narrow which must comply with water-quality standards exist shape of the Roanoke River Basin, varying in width in the Town Fork Creek Basin; however, the potential from 8 mi in reaches downstream from Roanoke to sustain base flows in the basin is high, thereby off Rapids Lake to about 25 mi near Williamston. The low- setting the effect of the point-source discharges. The flow discharge profiles were limited to the reach of the higher percentage in the Country Line Creek Basin is Roanoke River between Roanoke Rapids (site 181) and not reflective of numerous permitted discharges in the basin, but rather the low 7Q10 discharge determined at Williamston (site 200). Insufficient data in the lower the mouth. The existence of soils having low infiltra reaches along with unknown effects of tides on low tions rates in combination with irrigation withdrawals flows prevented development of low-flow discharges. in the lower portion of the Country Line Creek Basin The percentage of permitted NPDES flows to the 7Q10 result in loss of 7Q10 discharge (between sites 90 discharge at the gaging station at Roanoke Rapids and 91). (site 181) is about 18 percent.
36 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina SELECTED REFERENCES graphic Information and Analysis, North Carolina Department of Environment, Health, and Natural Barnes, C.R., 1986, Method for estimating low-flow statis Resources, 53 p. tics for ungaged streams in the lower Hudson River Kopec, R.J., and Clay, J.W., 1975, Climate and air quality, in Basin, New York: U.S. Geological Survey Water- North Carolina atlas: Portrait of a changing southern Resources Investigations Report 85-4070, 22 p. State, 1975: Chapel Hill, University of North Carolina Bingham, R.H., 1985, Low flows and flow duration of Ten Press, p. 92-111. nessee streams through 1981: U.S. Geological Survey Langbein, W.B., and Iseri, K.T., 1960, General introduction Water-Resources Investigations Report 84-4347, 325 p. and hydrologic definitions: U.S. Geological Survey Bondelid, T.R., Hanson, S.A., and Taylor, P.L., 1990, Tech Water-Supply Paper 1541-A, 29 p. nical description of the Reach File: U.S. Environmental McMahon, G., and Lloyd, O.B., Jr., 1995, Water-quality Protection Agency RF1/2/3 Draft, 17 p. assessment of the Albemarle-Pamlico drainage basin. Carter, R.F., Hopkins, E.H., and Perlman, H.A., 1988, Low- North Carolina and Virginia Environmental setting flow profiles of tu : Jpper Savannah and Ogeechee Riv and water-quality issues: U.S. Geological Survey ers and tributaries in Georgia: U.S. Geological Survey Open-File Report 95-136, 72 p. Water-Resources Investigations Report 88-4047, 169 p. Mitchell, W.B., Guptill, S.C., Anderson, K.E., Fegras, R.G., Daniel, C.C., III, 1989, Statistical analysis relating well yield and Hallam, C.A., 1977, GIRAS A geographic infor to construction practices and siting of wells in the Pied mation and retrieval system for handling land use and mont and Blue Ridge provinces of North Carolina: U.S. land cover data: U.S. Geological Survey Professional Geological Survey Water-Supply Paper 2341-A, 27 p. Paper 1059, 16 p. Daniel, C.C., III, and Payne, R.A., 1990, Hydrogeologic unit Musgrave, G.W., 1955, How much of the rain enters the map of the Piedmont and Blue Ridge Provinces of soil?, in Water: The yearbook of agriculture 1955: U.S. North Carolina: U.S. Geological Survey Water- Department of Agriculture, p. 151 -159. Resources Investigations Paper 90-4035, 1 sheet, scale Musgrave, G.W., and Holtan, H.N., 1964, Infiltration, /// Te 1:500,000. Chow, Ven, ed.. Handbook of applied hydrology A Evett, J.B., 1994, Effects of urbanization and land-use compendium of water-resources technology: New changes on low stream flow: Raleigh, University of York, McGraw-Hill Book Co., Section 12, p. 12-26. North Carolina Water Resources Research Institute Nelms, D.L., Harlow, G.E., Jr., and Hayes, D.C., 1995, Base- Report No. 284, 146 p. flow characteristics of streams in the Valley and Ridge, Fenneman, N.M., 1938, Physiography of Eastern United Blue Ridge, and Piedmont physiographic provinces of States: New York, McGraw-Hill, 714 p. North Carolina: U.S. Geological Survey Open-File Fransen, T, 1991, Hydrology for 1990, in Rulifson, R.A., Report 95-298, 52 p. and Manooch, C.S., III, eds., Roanoke River water flow National Oceanic and Atmospheric Administration, 1992, committee report for 1990: National Ocean and Atmo Climatological data annual summary: North Carolina: spheric Administration Technical Memorandum National Oceanic and Atmospheric Administration, NMFS-SEFC-291,p. 139-162. issued annually. Giese, G.L., and Mason, R.R., Jr., 1993, Low-flow character North Carolina Department of Environment, Health, and istics of streams in North Carolina: U.S. Geological Natural Resources: 1992, North Carolina lake assess Survey Water-Supply Paper 2403, 29 p. ment report: Division of Environmental Management, Goddard, G.C., Jr., 1963, Water-supply characteristics of Water Quality Section, Report 92-02, 353 p. North Carolina streams: U.S. Geological Survey Water- 1996, Roanoke River Basin-wide water quality man Supply Paper 1761,223 p. agement plan: draft report, 300 p. Hale, T.W., Hopkins, E.H., and Carter, R.F., 1989, Effects of North Carolina Department of Natural Resources and Com the 1988 drought on streamflow in Alabama, Georgia, munity Development, 1985, Geologic map of North North Carolina, South Carolina, Tennessee, and Vir Carolina: 1 sheet, scale 1:500,000. ginia: U.S. Geological Survey Water-Resources Inves Outlaw, G.S., and Weaver, J.D., 1996, Flow duration and low tigations Report 89-4212, 102 p. flows of Tennessee streams through 1992: U.S. Geolog Hayes, D.C., 1991, Low-flow characteristics of streams in ical Survey Water-Resources Investigations Report 95- Virginia: U.S. Geological Survey Water-Supply Paper 4293, 245 p. 2374, 69 p. Riggs, H.C., 1968, Frequency curves: U.S. Geological Sur Khorram, S., Chesire, H., Siderelis, K., and Nagy, Z., 1991, vey Techniques of Water-Resources Investigations, Mapping and GIS implementation of land use and land book 4, chap. A2, 15 p. cover categories for the Albemarle-Pamlico drainage 1972, Low-flow investigations: U.S. Geological basin: Raleigh, N.C., Computer Graphics Center, North Survey Techniques of Water-Resources Investigations, Carolina State University and the Center for Geo book 4, chap. Bl, 15 p.
Selected References 37 1973, Regional analyses of streamflow characteris 1928, Soil survey of Martin County, North Carolina: tics: U.S. Geological Survey Techniques of Water- Bureau of Chemistry and Soils, 32 p. Resources Investigations, book 4, chap. B3, 15 p. 1928, Soil survey of Person County, North Carolina: Seaber, P.R., Kapinos, P.P., and Knapp, G.L., 1987, Hydro- Bureau of Chemistry and Soils, 36 p. logic unit maps: U.S. Geological Survey Water-Supply 1940, Soil survey [of] Stokes County, North Caro Paper 2294, 63 p. lina: Bureau of Plant Industry, 39 p. Stedinger, J.R., and Thomas, W.O., Jr., 1985, Low-flow fre 1942, Soil survey [of] Warren County, North Caro quency estimation using base-flow measurements: U.S. lina: Bureau of Plant Industry, 37 p. Geological Survey Open-File Report 85-95, 22 p. Strickland, A.G., and Bales, J.D., 1994, Simulation of 1980, Soil survey of Vance County, North Carolina: unsteady flow in the Roanoke River from near Oak City Soil Conservation Service, 94 p. to Williamston: U.S. Geological Survey Water-Supply 1990, Soil survey of Bertie County, North Carolina: Paper 2408-A, 34 p. Soil Conservation Service, 115 p. Stuckey, J.L., 1965, North Carolina: Its geology and mineral 1992, Soil survey of Rockingham County, North resources: Raleigh, Department of Conservation and Carolina: Soil Conservation Service, 152 p. Development, 550 p. U.S. Geological Survey, 1961-94, Water resources data for Tant, PL., Byrd, H.J., and Horton, R.E., 1974, General soil North Carolina: U.S. Geological Survey Water-Data map of North Carolina: U.S. Department of Agricul Report, issued annually. ture, Soil Conservation Service map, 1 sheet, scale 1974, Hydrologic unit map: State of North Carolina: 1:1,000,000. 1 sheet, scale 1:500,000. Telis, PA., 1991, Low-flow and flow-duration characteris 1974, Hydrologic unit map: State of Virginia: 1 tics of Mississippi streams: U.S. Geological Survey sheet, scale 1:500,000. Water-Resources Investigations Report 90-4087, 214 p. Yonts, W.L., 1972, Low-flow measurements of North Caro 1992, Techniques for estimating 7-day, 10-year low- lina streams: Raleigh, North Carolina Department of flow characteristics for ungaged sites on streams in Water and Air Resources, 236 p. Mississippi: U.S. Geological Survey Water-Resources Investigations Report 91-4130, 143 p. Yonts, W.L., Giese, G.L., and Hubbard, E.F, 1973, Evapora Terziotti, S., Schrader, T.P, and Treece, M.W., Jr., 1994, tion from Lake Michie, North Carolina 1961-71: U.S. Estimated water use, by county, in North Carolina, Geological Survey Water-Resources Investigations 38- 1990: U.S. Geological Survey Open-File Report 94- 73, 27 p. 522, 102 p. Zalants, M.G., 1991, Low-flow frequency and flow duration U.S. Department of Agriculture, 1910, Soil survey of of selected South Carolina streams through 1987: U.S. Caswell County, North Carolina: Bureau of Soils, 28 p. Geological Survey Water-Resources Investigations 1912, Soil survey of Granville County, North Caro Report 91-4170, 87 p. lina: Bureau of Soils, 44 p. Zembrzuski, T.J., Jr., Hill, C.L., Weaver, J.C., Coble, R.W, 1918, Soil survey of Halifax County, North Caro- and Gunter, H.C., 1991, North Carolina floods and lina: Bureau of Soils, 47 p. droughts, in National Water Summary 1988-89 1925, Soil survey of Northampton County, North Hydrologic events and floods and droughts: U.S. Geo Carolina: Bureau of Chemistry and Soils, 48 p. logical Survey Water-Supply Paper 2375, p. 425-434.
38 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina i 1 "5 i Q.P § 0 o o <; o o o o o o o o y « 3 o 8 g N *~ |f~< Z to E S 2 JL "« a "* C 3 C C C8 O i O4 O4 3 04 ^C ^ | - E ^ iz ^ C O) O O CD o *& ^ ^ "H^H 0^ OO o\ CD NO O> o § r- 03 o "5. ON O> ien ' i
CD gnl adAj ajjs - 04 Ol .-, 0) 01 01 04 CN O4 04 04 "u CD _o .E m m m m rr, rr, rr. m rr, m m 5 ID 8 O O 3 o O O o O O O O O 8 O O O "^ > O *- 0) o O O O O o O O O O O O o o O o 03 Si o 3 _c o o 01 - ^^ rr o ON ol NO ^ rr, -^~ f** ON ON CD Q -rt Q m' p = fi^c t-H 00 o 00 O4 0 NO ' 05 £ X 04 m ^ f- 5 d f-
03 --H p | SD NO NO o> ^3 u s fr, rr, rr, m D o 1^ fr o S ° 3 1) o "S 9. 3 fU "05 S C+H ' c la 1 u o JJ 03 |o 3 Q. 0) * s U T3 CO " 10 Prestonvi C c aboveSEOver c3 03 Franciscoar c Ol eekFnear s I 1 s ^ Asburyar m NC89nea *" § = CO s & g 13 «"§ 2; B DC Q o S X3 C3 to os C X3 S c3 13 rt M 00 c s a U - £ S 3 iverne "S. s tH o- 2
Additional Tables 39 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) o Liiu , AIJUCUI. Jiiii^, i^/^v, iiwi ay^nu-auit, Ji_>v/, stwagt &iiiui;iii uuiicui. oiita auautu 111 gia^ iiiuiv-aic uiu&t aiiws lui wiuv.ii luw-uuw v-iiaiav-itusuv-a uavt utwii utvtiuytu. i tnuu ui it^wiu iwi ^uniuiuuus-itv-uiu 1 sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] Characterow Number of 6 measure Drainage Hydrologic a) ments for par x USGS USGS Tributary a. o downstream Station name Latitude Longitude County topographic area, unit Period of record tial-record to - order number quad name (mi2) code sites 55' t/5 X Zero- o' Flow (0 flow D) 36°24'06" 80°08'21" a3 18 02068734 Dan River near Dodgetown Stokes Danbury 335 Roanoke 03010103 2 1970 3 0 TJ River 5"§, 19 02068762 Dan River near Walnut Cove 36°19'36" 80°05'44" Stokes Belews Lake 355 Roanoke 03010103 2 1970, 1974 5 0 3-(0 River ^ 20 02068856 Town Fork Creek near Poplar Springs 36°16'24" 80°16'27" Stokes King 20.1 Dan River 03010103 2 1959, 1963, 1981 3 0 5" 21 02068891 Buffalo Creek at Germanton 36°15'51" 80°13'47" Stokes Walnut Cove 15.0 Town Fork 03010103 2 1959, 1963 2 0 o Creek Joa. w 22 02068892 Neatmans Creek near Germanton 36°16'58" 80°15'26" Stokes King 17.0 Town Fork 03010103 2 1959, 1963, 1981 3 0 3 Creek D) 36°16'45" 80011'31" (0 23 02068904 Vbss Creek near Walnut Cove Stokes Walnut Cove 4.89 Town Fork 03010103 2 1970. 1973-74 5 0 5' Creek
(D 24 02068911 Old Field Creek near Walnut Cove 36°16'37" 80°10'05" Stokes Walnut Cove 16.0 Town Fork 03010103 2 1959, 1963, 1981 3 0 3D O Creek D) 3 36°17'39" 80°08'50" O 25 02068931 Milts Creek at Walnut Cove Stokes Walnut Cove 9.86 Town Fork 03010103 2 1955-56, 1963 3 0 PT (D Creek 5 02068980 36Q17'29" S0°08'29" Stokes Walnut Cove 113 Dan River 03010103 2 1925, 1949-1957, 1959, 39 0 (D 26 Town Fork Creek at Walnut Cove 1961-63, 1966, 1970, 00 D) 1973, 1974 tt 27 02068988 Lick Creek at Walnut Cove 36°17'10" 80°08'13" Stokes Walnut Cove 13.5 Town Fork 03010103 2 1959, 1963, 1981 3 0 z Creek 03 3" 36°19'09" 80003'01" o 28 02069000 Dan River at Pine Hall Stokes Belews Lake 501 Roanoke 03010103 1 Oct 1923 * Mar 1926, N/A N/A D) River Apr 1986 -Dec 1990, 5" Feb 1991 D) 2 1975-77, 1979-81, 1983 33 0 29 02069032 Belews Creek at Belews Creek 36°14'25" SOW 10" Forsyth Belews Creek 22.8 Dan River 03010103 2 1959, 1963 2 0 30 02069034 East Belews Creek near Grims Crossroads 36°12'20" 80°02'57" Forsyth Belews Creek 5.52 Belews 03010103 "> 1959, 1963 2 0 Creek 31 02069036 East Belews Creek near Belews Creek 36°14'20" 80°03'00" Forsyth Belews Creek 16.9 Belews 03010103 2 1963 1 0 Creek "8 0 lS-o- ll o O o O O o < o u ^ Y A M H- 0) £ ca E g w ± 'w s 3 m NO f-~ i i 0 3 C C CO O c^ o> ^ 3 Z (!>' ? OJ "H
£ u ^ 3 Ui u i. ^ c§ 10 u ^i qj > I-.--I L. "U 3 O I 'i 1 ,5; fl fX f^l rY 1 1 S 1 1 ||| 1 oooo ^ 1 1 Q « Q c§ Q « Q S Q Q Q Q Q Q n o V o -c .2 oq mi 0 -3 0 10 tNI^ C O "^ 2 S r-i m tN T* ' r- O JO c .c W5 .2 d> C fj 4J u y *ra ^N C3 CO Q- S "fH foriteswl iswaterye (32 = BelewsL; te c c c a O u 3 3 o ^ o 1 & | 1 8 O i 1 e i1 55 »5 « & on & OS ^ -a d>o . . . . _ _ oo f^ SO b ob ~ 3 ^ ?n Jn £H 00 r-4 % ^_ ON oo oo ON O O 'S 0 o O O o o ON ON ON "S "2 oo oo oo r- r*-* C3 f\ .C g ^.J 00 y d>o to ?S ON ON oo fsi .S "^ Vl i/-» p on £ f? ON ri r-t «N C-4 § r\ tN -3 3 m °- °- ° ~^ ^ i> SO t+2 iT m fi m mj m m ffl «3 £"H e o ~ii D o a 3 Additional Tables 41 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) o Liiii , sifucut; lime, i>//-v, iiui appiieauic, ou/vy, sewage tlllllCUl uuiiiui. ones siiaueu Hi giaj mui^aic must sues lui wiiii^ii ivw-uuw i^uaiai^ieiisui^s nave uveu utvciupeu. rciiuu ui lecuiu lui i^uuuuuuus-iei^uiu sites (site type 1 ) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] Number of o measure USGS Drainage ments for par CharacteristicsandPiow x USGS Tributary Hydrologic a. o downstream Station name Latitude Longitude County topographic area, unit - Period of record tial-record to 0) - order number quad name (mi2) code ~ sites Zero- 55 Flow flow 50 02071000 Dan River near Wentworth 36°24'45" 79°49'35" Rockingham SWEden 2 1,035 Roanoke 03010103 1 Dec 1939 - Oct 1994 N/A N/A River rofilesfor 51 02071003 Rock House Creek near Wentworth 36°23'48" 79°47'24" Rockingham Southwest Eden 18.4 Dan River 03010103 2 1954, 1959, 1963 3 0 52 02071033 Buffalo Creek above Eden 36°29'26" 79°51'17" Rockingham Southwest Eden 7.41 Dan River 03010103 2 1959, 1963, 1981 3 0 36°29'06" 79°52'18" (D 53 02071063 Buffalo Creek Branch near Stoneville Rockingham Southwest Eden 3.11 Buffalo 03010103 2 1954, 1970, 1973, 1981 8 0 (D Creek 0 a(D 54 02071110 Buffalo Creek near Eden 36°28'41" 79°49'16" Rockingham Southwest Eden 16.3 Dan River 03010103 2 1954, 1963 3 0 rr\ inStreams 55 02071113 Buffalo Creek near Stoneville 36°28'21" 79°48'26" Rockingham Southwest Eden 21.3 Dan River 03010103 2 1954, 1959, 1963, 1981 4 0 56 02071500 Dan River at Eden 36°29'09" 79°45'24" Rockingham Southwest Eden l,133a Roanoke 03010103 1 Aug 1929 -Sept 1949 N/A N/A River 36°31'31" 79°45'57" (D 57 02074000 Smith River at Eden Rockingham Northwest Eden 538 Dan River 03010103 1 Oct 1939 - Sept 1994 N/A N/A 36°28'18" 79°44'52" RoanokeRiv 58 02074018 Dan River near Eden Rockingham Southeast Eden 2 1,682 Roanoke 03010103 2 1970, 1973-74 6 0 River 59 02074021 Dan River below SEO near Eden 36°28'26" 79°44'11" Rockingham Southeast Eden 2 1,683 Roanoke 03010103 2 1970 3 0 River (D 36°28'44" 79°42'12" GO 60 02074056 Town Creek near Eden Rockingham Southeast Eden 12.3 Dan River 03010103 2 1954, 1959, 1963, 1981 4 0 Q> (0 3' 61 02074062 Machine Creek at SR 1974 near Eden 36°28'38" 79°42'02" Rockingham Southeast Eden 2.28 Town Creek 03010103 2 1954, 1959, 1963, 1981 4 0 z o 62 02074082 Dan River at NC 700 at Eden 36°29'55" 79°40'53" Rockingham Southeast Eden 2 1,708 Roanoke 03010103 2 1970, 1973 5 0 3. River O Q> 63 02074188 Mountain Run near Draper 36°32'00" 79°38'50" Rockingham Northeast Eden 7.30 Cascade 03010103 2 1958, 1963 2 1 5'O_ Creek Q> 64 02074218 Dan River near Mayfield 36°32'29'T 79° 3671" Rockingham Brosville 2 1,760 Roanoke 03010103 1 Sept 1976 - Nov 1984 N/A N/A River 2 1968-72, 1974-75 25 0 65 02074282 Wolf Island Creek at Reidsville 36°22'20" 79°41'10" Rockingham Reidsville 3.71 Dan River 03010103 2 1954, 1970, 1973-74, 19 0 1976-81 66 02074292 Wolf Island Creek near Reidsville 36°23'28" 79°40'11" Rockingham Southeast Eden 7.10 Dan River 03010103 2 1970, 1973-74 8 0 "2 o oib gl o «i;oor4ooo-«j;-^-^^^oo o >- *" »- O isJ «C ^5i *^~ Q) 3 o O MI Z Z1 V .Q Additional Tables 43 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) o Liiu , av|uoiw uiiiw, n/.n, iiui appuv^auit, Liuv_7, atvva^c diiudii uuiiaii. LMI^S auaucu in &L&J iiiun-aiv; iiiuat ones lui win\-ii luvv-iiuw i~uaiai~LdiMii.;> nave ut^n utvtiu^fcu. rtiiuu ui itiuiu lui v^uuiiiiuuus-itcuiu sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] -!«» Number of Characterow measure indexeno. USGS Drainage Hydrologic Q. ments for par uses Tributary downstream Station name Latitude Longitude County topographic area, unit - Period of record tial-record to 0) order number quad name (mi2) code * sites 0) <7> Zero- o' Flow w flow D) 3 36°21'20" 79°26'19't Q. 82 02075208 Country U ne Creek near Locust Hill Caswell Cherry Grove 22.6 Dan River 03010104 2 1959, 1963, 1966, 1968 4 0 TJ 5^ 83 02075209 Hostler Branch at Locust Hill 36°21'58" 79°26'27" Caswell Cherry Grove 6.95 Country Line 03010104 2 1966, 1968 2 0 ~ Creek 8 3" 84 020752 1 7 Country Line Creek near Yancey ville 36°23'07" 79°21'31" Caswell Yanceyville 46.8 Dan River 03010104 2 1970, 1973-74 6 0 % 85 02075220 Country Line Creek at Yanceyville 36°23'30" 79°19'54" Caswell Yanceyville 50.3 Dan River 03010104 2 1954, 1956-62, 1966, 23 0 (D O 1970, 1973 (D Q. 86 02075230 South Country Line Creek near 36° 18*4?" 79° 1836" Caswell Anderson 6.57 Country Line 03010104 2 1953, 1959, 1963, 1966, 6 5 O> Hightowers Creek 1968, 1970 (D Q) 36°20'44" 79°17'27" 3 87 02075240 South Country Line Creek near Topnot Caswell Anderson 16.4 Country Line 03010104 2 1962-69 20 8 0)5' Creek 88 02075250 Penson Creek near Yanceyville 36°20'54" 79°17'34" Caswell Anderson 12.2 South 03010104 2 1959, 1963-68, 1970 19 4 (D 3J Country O Line fi) 3 Creek 0 ff 89 02075260 South Country Line Creek aear 36°20'50" 79°17'24" Caswell Anderson 29.0 Country Line 03010104 2 1949*53, 1956*60, 1962» 33 4 1'3D Yanceyville Creek 66, 1968 ^ 36°26'57" 79°15'12" 0 DO 90 02075268 Country Line Creek near Hamer Caswell Yanceyville 113 Dan River 03010104 2 1966, 1968 0 Q) _5'(0 91 02075270 Country Line Creek near Semora 36°29'54" 79°12'25" Caswell Leasburg 131 Dan River 03010104 2 1954, 1956-68, 1970, 38 1 z 1973-74 o 3 92 0207527050 Country Line Creek at NC 57 at Milton 36°32'16" 79°12'04" Caswell Milton 138 Dan River 03010104 2 1974-84 35 0 0 fi) 93 02075500 Dan River at Pace s (Va.) 36°38'32" 79°05'23" Halifax (Va.) Oak Level 2.550 Roanoke 03010104 1 Nov 1950 - Sept 1994 N/A N/A 0_5' River Q) 94 02077 1 8 1 30 Hyco Creek at SR 1767 near Baynes 36°1715" 79°15'43" Caswell Anderson 5.00 Dan River 03010104 2 1974-81 19 0 95 02077182 Hyco Creek near Hightowers 36°19'07H 79°13'35" Caswell Ridgeville 16.9 Dan River 03010104 2 1959, 1963, 1966, 1968 4 2 96 02077 1 92 Panther Creek near Frogsboro 36°19'54" 79°12'31" Caswell Ridgeville 5.49 Hyco Creek 03010104 2 1966, 1968 2 0 97 02077200 Hyco Creek near Leasburg 36°23'57" 79° 11 '50" Caswell Leasburg 45.9 Dan River 03010104 1 Aug 1964 - Sept 1994 N/A N/A 98 020772 14 Reedy Fork Creek near Leasburg 36°25'06" 79°13'57" Caswell Leasburg 9.29 Hyco Creek 03010104 2 1964-66, 1968, 1970 9 6 "2 H- ra -n O $ o o i a^ 5 o ^HO^H ^H i ^H rt1 > > O O4 O If § a> l^^^ 1^ -"S OfiS ra Occcce c g Jsg^ b^ a 0£ o S a rjj £* c ij >% >-» >- >% >% >% ^ Sow tu tu k> _k> i> k> £* ij ^C ij ^l* i-^ . «. "H, e Tt2 u nj ii> ii> ii> ~Sf u 5n tu o u o o o Q, 0 O QJ fU U U U .S *U .5 5J M I-H ;>^ ^ ;>^ I rt g ^uuuuugugu ^^ ::d aa a o £ -OOOOOO3o3o JS-Q-S 'S'S < 1 aaaaaa'^^I^'I^'M^'^ i^Ta 1 aJ& ouw,OOo onwOO a Z J2 ^ E v ^O r* OO ON O-1 r^i TJ~ tn ^^ ^O ^** OO C? o i) . . (0 ^ ^H _ ^H ^H 01 O1 O1 Additional Tables 45 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) [mi2, square mile; N/A, not applicable; SEO, sewage effluent outfall. Sites shaded in gray indicate those sites for which low-flow characteristics have been developed. Period of record for continuous-record sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] owCharacter Number of d measure x USGS USGS Drainage Hydrologic ments for par Tributary o downstream Station name Latitude Longitude County topographic area, unit Period of record tial-record to 0) (mi2) sites Q) order number quad name code ft (0 Zero- o Flow in flow B) 36°25'08" 79°06'14" Q. 116 02077252 South Hyco Creek near Longs Store l Person Olive Hill 61.9 Hyco River 03010104 2 1959, 1963 2 0 TJ 36°24'OI" 0 117 02077254 Richland Creek near Roseville 79W42" Person Olive Hill 5.79 South Hyco 03010104 2 1964-66, 1968, 1970 8 2 _. Creek in(D 5« 118 02077256 Richland Creek near Longs Store 36°25'04" 79°05'58" Person Olive Hill 7.96 South Hyco 03010104 2 1959, 1963, 1965 4 0 Creek to 5" 119 02077258 Duck Creek near Concord 36°26'36" 79°05'05" Person Olive Hill 4.30 South Hyco 03010104 2 1965 2 0 » Creek Q. to 120 02077260 South Hyco Creek near Concord1 36°27'48" 79°05'34" Person Olive Hill 76.5 Hyco River 03010104 2 1953-54, 1956-64 28 1 (D3 B) 121 02077261 Sargents Creek near Ceffo 36°27'06" ?9°03t27't Person OHve Hill 1.77 Hyco River 03010104 2 1965-66, 1968 4 0 (0 5' 122 0207726250 Cane Creek near McGehees Mill 36°30'08" 79°05'53" Person Alton 3.05 Hyco River 03010104 2 1965 1 0 36°30'07" 79°05'53" (D 123 0207726275 Cane Creek tributary 4 near Person Alton 0.06 Cane Creek 03010104 2 1965 1 1 3) McGehees Mill 0 B) 3 36°30'49" 79°05'34" 0 124 0207726350 Cane Creek tributary 3 near Person Alton 1.80 Cane Creek 03010104 2 1965 1 0 (D McGehees Mill 3J < 125 0207726365 Unnamed tributary to Cane Creek 36°30'48" 79°05'34" Person Alton 0.02 Cane Creek 03010104 2 1965 1 1 (D tributary 3 near McGehees Mill tributary 3 DO B) 36°30'49" 79°05'26" (0 126 0207726375 Unnamed tributary to Cane Creek Person Alton 0.02 Cane Creek 03010104 2 1965 1 1 tributary 3 near McGehees Mill tributary 3 z 0 127 0207726410 Cane Creek tributary 2 near 36°31'38" 79°04'05" Person Alton 0.69 Cane Creek 03010104 2 1965 1 0 s McGehees Mill 0 B) 128 0207726425 Unnamed tributary to Cane Creek 36°31'34" 79°04'11" Person Alton 0.48 Cane Creek 03010104 2 1965 1 0 0. 5' tributary 2 near McGehees Mill tributary 2 B) 129 0207726450 Unnamed tributary to Cane Creek 36°31'32" 79°03'44" Person Alton 0.79 Cane Creek 03010104 2 1965 1 0 tributary 2 near McGehees Mill tributary 2 130 02077279 Hyco River tributary near 36°30'38" 7903'12" Person Alton 0.03 Hyco River 03010104 2 1965 1 1 McGehees Mill 131 02077300 Hyco River at McGehees Mill 1 36°31'02" 79°01'42" Person Alton 198 Dan River 03010104 1 Sept 1964 - Sept 1973 N/A N/A a o o i g.| §| __ ! O CO O O O ' *?! cNOOOl fN^**«<^' ^fO o < !L> 5 M -2 0 S Z § ^ ^ 3 E S « ± '55 j O 3 c C CO O ^f! 1 1 r<*( l|^ oO ^O O^ ' ' ^fj C-l *O ' i ^O "^ -<^ "^ <£ ' ' "*^" 3 Z 0) "£* """ fc*^ V> «ss, *-C! C^J **v C*J C E u" ^ Z IS Z C O O CO ^ ON OO GO O * o o u II 5 S 1 1 1 S S S S- S S 1 i | o a> o "o a, a, ON <§? Si If H" II' tl S. 0^ 0? O^^vo** 0 C ' < -1-H ws «5 wj w O A) 00 U) 60 "p £ !E g S5 C -C ---. ^ «S ra v^ *jO ' C ^~' * C *^ ^~J *^ *^ *^ " C< o 5 c itesforwh: iswaterye; ClusterSp 3OOO ^ o^3 OOOO O^ «to3 = o | o cr O «!!!>xxi< |S 1xS | 1115xxxx 11x-3 illgpwi^S '-3 OOO 3 0^ OOOO O»3 ,SS . fa 4) < Ooiosas u oiU oioioiQi oiU >>z a 1 0 0 ^* 5 -c c ^ u ~ C CCC3G C C^5«C3CCC CC CC'C o o o o o 0 £ S "* & ex £ £ <£ £ cS c^ffi c^^cxl £ £ £cxO 2 'w a> V", T3 OO ro£o?Or~- OO ^ONO ' V~) ro Q Of^J ONOOfS) U) 3 t^* "^" OO^f 1*^ ^ ro*O roOO 1*^ v^ 1*^ ^* Vj f\| ~ ON O r-l OO 00 OO F ^O ?O ro T)- ro CN) ro r*> 04 OO T* £ u o O5 Vj */*! V^ l/*j l/*j Vl V*( *O V~j V^ Vl V^ V^ ^" ^T C "S M OO ON ONOOOOOO OO OO OO OO OO OO OO- OOOO OOOOOO 5 r- r^ _e 0 "u3 ° ...... _. r = ;r si =ri a> S3 v o» ^ Bc5ro?i ^o r5S ro So ro ci Ko^ rofN^ '** .2 3 ^* o *t «ri NO So ci ONJn rorr-.'^-NO N£>« r-jcj** t/J ^ rO ro n n rs r^t ro ra ro r) o o r) CN ro co ro ro CO ^ 0, WD NO a ^ CO ro ro CO ro CO ro ro CO cr-, ro ro CO fO CO CO ro rO ° -o C O y tu u tu o c3 C t3 "o ^> <~w !L> _, o tS <3 43 « IS x «1 T3I o *- S ^ ^ oH - ? 5 a> >, ^2^ M 3 w "es u ^.^^ B"! Sfa^ ^" S *2ofe* ^ «-^^/«« £ '"S S £ o < «' § S [y »-P«J P a S * ^ ! * 1 1 ? 5 | ^ »a? OD rt (/) .yrt j=as 15 ^ ||||^| a | a '1 i 8 §g c^J "a, a u ^ y i-nCJOUga; Sj<3 !U1>'D ^ *3 fa £ < 1 Q ^r (J ^ ^ ^ ^^ JUS ^* ^» L. £ < ? 6 Additional Tables 47 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) o Hiii , aijuait; unit, i^/^v, uui ajjjjiicaui^, ouw, s^wagt ^iiiuciu uuiiaii. oiita aiiau^u 111 gitij' iHUicait muse silts IVH wiin-u ivw-iiuw \*iiaia\*i&iiaiica navt* u^^ii ui^v&ivjjvu. i ^iivu vi i^^viu ivi ^vmiuiuuus-i^^uiu sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] Number of owCharacter measure indexeno. USGS Drainage Hydrologic §. ments for par- USGS Tributary County topographic unit ~ Period of record tial-record downstream Station name Latitude Longitude area, to order number quad name (mi2) code | sites CO* Zero- o' 55 Flow CO flow D> 36°32'20" 73044-59- Q. 150 02078214 Wolfpit Run near Cornwall Granville Virgilina 1.95 Aarons 03010104 2 1966 1 1 T> Creek 151 0207901030 Grassy Creek at SR 1325 near Oak Hill 36°25'35" 78°46'10" Granville Triple Springs 1.88 Roanoke 03010102 2 1974, 1976, 1978, 1980 6 0 1 River £ 152 02079022 Grassy Creek at Cornwall 36°28'20" 78°39'52" Granville Satterwhite 20.9 Roanoke 03010102 2 1966, 1969 2 1 9 River 9 O 36°27'53" 78°38'46" (0 153 02079032 Mountain Creek near Cornwall Granville Satterwhite 11.0 Grassy 03010102 2 1966 1 1 Q. Creek 3 154 02079100 Little Grassy Creek near Stovall 36°28'34" 78*3616" Granville Stovall 22.9 Grassy 03010102 2 1956-59, 1961-64,1966, 24 1 D> 3 Creek 1969 5'(0 155 02079101 Grassy Creek at SR 1436 near CornwaD 36°29'22" 78°37'08" Granville Stovall 61.2 Roanoke 03010102 2 1981,1983*92 46 0 5 River (D 3) 36°30'49" 78°40'17" 0 156 02079182 Little Johnson Creek near Cornwall Granville Nelson 14.3 Grassy 03010102 2 1955-56 2 1 D> 3 Creek O ff 157 0207920210 Grassy Creek at SR 1443 near Bullock1 36°32'02" 78°35'53" Granville Clarksville 103 Roanoke 03010102 2 1974-76 7 1 5 South River 9 158 0207920940 Gills Creek at SR 1430 near Stovall 36°26'10" 78°32'37" GranvUle Stovall 13.8 Island Creek 03010102 2 1974-76, 1978-81,1983- 43 2 UJ D> 89 CO 159 02079210 Island Creek near Bullock 36°29'42 Additional Tables 49 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) o Liin , squai^ unit, i>//-\, nui appiiuauic, OLiVA scwagt cinucm uuuaii. ones Miaucu 111 giay mui^aic must silts iui wmuii IUW-HUW uiiaiauitiisuts uavt uctii ucvciuptu. rtinju ui ic^uiu iui cuuiiiiuuua-ittuiu sites (site type 1 ) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] owCharacter Number of 0 measure x USGS USGS Drainage Hydrologic 0) ments for par Tributary a. S downstream Station name Latitude Longitude County topographic area, unit & Period of record tial-record to 0) - order number quad name (mi2) code sites (0 Zero- o' w Flow .. (0 flow 0) 36°30'00" 77°55'10" a3 179 02079867 Big Stone House Creek near Enterprise11 Warren Littleton 22.0 Roanoke 03010106 2 1955 1 0 TI River 5" 180 02080053 Deep Creek near Thelma 36°27'05" 77°46'58" Halifax Thelma 23.5 Roanoke 03010106 2 1961-62, 1969 3 1 3"(0 River 36°27'37" 77°38'04" w 181 02080500 Roanoke River at Roanoke Rapids Halifax Roanoke 8,384 Roanoke 0301010? 1 Dec 1911 - Sept 1994 N/A N/A 191 02080870 Gumberry Swamp near Jackson 36°21'25" 770 28'0]" Northampton Boones 20.0 Roanoke 03010107 2 1957, 1961. 1965-68 10 0 Crossroads River 192 02080881 Lily Pond Creek below SEO near 36°22'23" 77°26'00" Northampton Boones 1.60 Gumberry 03010107 2 1970, 1973-74 5 0 Jackson Crossroads Swamp Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) [mi", square mile; N/A, not applicable; SEO, sewage effluent outfall. Sites shaded in gray indicate those sites for which low-flow characteristics have been developed. Period of record for continuous-record sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] Number of d measure * USGS USGS Drainage Hydrologic Q. ments for par § downstream Station name Latitude Longitude County topographic area, ri u "^ unit 5* Period of record tial-record order number sites 0) quad name (mi2) code | (7) Zero- Flow .. flow 193 02080948 Bridgers Creek near Rich Square 36°15'23" 77°20'10" Northampton Rich Square 6.53 Roanoke 03010107 2 1970, 1973 5 1 River 194 02081000 Roanoke River near Scodand Neck 36°12'34" 77°23'03" HaOfax Scodand Neck 8,671 Atlantic 03010107 1 (discharge) N/A N/A Ocean Oct 1940 - Sept 1956 (gage height only) Oct 1985 - Sept 1994 2 1983 1 0 195 02081022 Roanoke River near Oak City 36°00'50" 77°12'55" Martin Woodville 8,813 Atlantic 03010107 2 1969, 1972, 1983, 8 0 Ocean 1986-87 1 (gage height only) N/A N/A July 1987 - Sept 1994 (discharge)3 Oct 1987 - Sept 1990 196 02081024 Indian Creek near Woodville 36°03'29" 77°10'40" Bertie Woodville 10.3 Roanoke 03010107 2 1961 1 1 River 197 02081028 Roanoke River at Hamilton 35°56'50" 77°12'10" Martin Hamilton 8,886 Atlantic 030 1 0 1 07 1 (gage height only )4 N/A N/A Ocean July 1987 - Sept 1994 (discharge)3 . Oct 1987 -Sept 1990 198 02081042 Etheridge Swamp at Oak City 35°58'27" 77°18'32" Martin Oak City 24.0 Conoho 03010107 2 1959 1 1 Creek 199 02081050 Conoho Creek at Oak City 35°58'19" 77°17'55" Martin Oak City 40.0 Roanoke 03010107 2 1959, 1964-66, 1968, 8 4 River 1970 > 200 02081054 Roanoke River at Williamston 35°51'40" 77°02'20" Martin Williamston 9,070 Atlantic 03010107 2 1983 1 0 Q. Q. Ocean tionalTabI 1 (gage height only) N/A N/A Dec 1985 - Sept 1994 (discharge)3 Oct 1987 - Sept 1990 Table 5. Summary of continuous- and partial-record gaging stations in the Roanoke River Basin study area in North Carolina where records of gage height and streamflow were collected (Continued) [mi2, mile; N/A, ;; SEO, sewage effluent outfall. Sites shaded in gray indicate those sites for which low-flow characteristics have been developed. Period of record for continuous-record sites (site type 1) shown in months and years; period of record for partial-record sites (site type 2) shown is water years in which discharge measurements were made.] Number of Characterow measure Siteindexno. USGS USGS Drainage Hydrologic ments for par Tributary Sitetype downstream Station name Latitude Longitude County topographic area, unit Period of record tial-record to order number quad name (mi2) code sites Zero- o'£ Flow CO flow 0) 35°45'58" 77003' 10" a 201 02081065 Smithwick Creek near Beargrass Martin Williamston 12.0 Sweetwater 03010107 2 1959, 1965-68 7 2 TJ Creek 1 202 02081071 Ready Branch above Dog Branch 35°47'20" 77°03'40" Martin Williamston 9.60 Sweetwater 03010107 2 1964 1 0 3CO1 near Williamston Creek T 203 02081079 Dog Branch near Williamston 35°47'20" 77°03'40" Martin Williamston 6.00 Ready 03010107 2 1964 1 0 CD Branch (D O 35°47'20" 77°03'40" (D 204 02081080 Ready Branch near Williamston Martin Williamston 16.0 Sweetwater 03010107 2 1949-54, 1957-59, 25 2 a Creek 1963-64 ! 205 02081094 Roanoke River at Jamesville 35°48'48" 76°53'37" Martin Jamesville 9,247 Atlantic 03010107 1 (gage height only) N/A N/A 0) 3 Ocean Oct 1990 - Sept 1993 5"CO 206 02081096 Cashie River near Lewiston 36°08'43" 77 214 0208112155 Cashie River above SEO at Windsor 35°59'40" 76°56'34" Bertie Windsor South 178 Roanoke 03010107 2 1970, 1973-74 4 0 River 215 0208112253 Broad Branch at Windsor 35°58'56" 76°56'54" Bertie Windsor South 4.10 Cashie River 03010107 2 1970 1 1 216 02081123 Roquist Creek near Drew 36°00'37" 77°02'53" Bertie Republican 27.7 Cashie River 03010107 2 1961 1 1 "H _ i 6s >»o 0 "S di Q. ^ S" O <£ o o O 3 £ C ]« £ o\ < < 3 g ** " z Z S O *** CJ \o Ui O s ^^ ON ON O . ON ON 'O 0 so 0) O CJ "5 cA O §" S *** '-4- O ft o V~t |§ a> u ^ I ^ gON Q. 1 £>3 ON o rt° S 1 _ bJL> o ON ON ip-4 f ^ >!_/ ^^ T3 4J edAj ens 04 ^H CN C4 ^ ^13 1c > ^* S 0 0 o *- .s j. - ya ^ i w Q- I o 1 ^ 0 « c "H -C Ul *> ** ^> » ^ CO O) *n S 03 5 5 ^. 3 o n o o O 1 ^ o § 1'^ O | |'i 4-1 Crt 1 CL! S 1 d O O ^ O o -C J3 c fi» U , _ c C3 rl 8 'S 'S '£ O D o CO ^ ON C i" (-Q « 1 ^ OQ . . . . ^f- 'E- *r?- 0) . rj ^t 00 m 3 o ri o ON '5 F- ON 5D ON "*oo fn .s* I "oo' *T3 crt c r£ ^ ^ ^ J§ ° 13 Additional Tables 53 Table 7. Magnitude and frequency of annual low-flow characteristics at partial-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina [mi2, square mile; water years, annual periods from October 1 to September 30; (ft3/s)/mi2, cubic feet per second per square mile; N/A, not available.] Number of Low-flow characteristics 6 USGSdownstream measure unitannualAverage ordernumber Drainagearea 32[(ft/s)/mi]flow in cubic feet per second X Period of ments o Station name 2(mi) record, water years Zero-flow 0 aCM W7Q10 o a 0 s 55 LL CO 14 02068720 Snow Creek near Prestonville 22 7 1955-56, 1964-68, 1970, 19 0 1.2 1.7 10.5 9.0 8.3 1980 23 02068904 Voss Creek near Walnut Cove 4.89 1970, 1973-74 5 0 1.2 0.5 1.2 1.2 1.0 25 02068931 Mill Creek at Walnut Cove 9.86 1955-56, 1963 3 0 1.2 0.9 2.9 2.7 2.3 26 02068980 Town Fork Creek at Walnut Cove 113 1925, 1949-1957, 1959, 39 0 1.2 8.9 21.8 20.0 17.2 1961-63, 1966, 1970, 1973, 1974 33 02069044 West Belews Creek near Walnut Cove 1 12.0 1955, 1959, 1963 3 0 1.2 1.2 2.5 2.3 2.0 36 02069410 Big Beaver Island Creek near Madison 23.8 1953-59, 1961-63, 1966 29 0 1.2 1.0 5.6 4.8 4.0 40 02070558 Boaz Creek near Stone vi lie 2.48 1970, 1973 6 0 1.2 <0.1 0.2 0.3 0.1 42 02070576 Mayo River tributary above SEO near 1.16 1970, 1973 6 0 1.2 <0.1 0.2 0.2 0.1 Mayodan 47 02070720 Hogans Creek near Madison 23.9 1954, 1956-64, 1966 27 0 1.1 1.3 5.8 5.3 4.2 49 02070930 Jacobs Creek at NC 704 near Madison 36.2 1954, 1959, 1963-67, 13 0 1.1 1.7 8.1 7.0 5.4 1969, 1970 51 02071003 Rockhouse Creek near Wentworth 18.4 1954, 1959, 1963 3 0 1.0 0.9 5.0 4.2 3.6 65 02074282 Wolf Island Creek at Reidsville 3.71 1954, 1970, 1973-74, 19 0 0.9 0.3 0.8 0.9 0.6 1976-81 67 02074360 Wolf Island Creek near Pelham 68.7 1954, 1956-64, 1966, 59 0 0.9 2.3 12.3 11.8 8.3 1968, 1970, 1974-79, 1981, 1983-84 71 02075090 Hogans Creek near Providence 98.4 1953-54, 1956-60, 1963, 29 2 0.9 1.2 10.4 9.5 6.0 1966, 1968, 1970 73 02075124 West Prong Moon Creek near Yanceyville 4.97 1959, 1963, 1966, 1968 4 0 0.9 0 1.2 1.2 0.6 74 02075142 East Prong Moon Creek near Yanceyville 7.15 1959, 1963, 1966, 1968 4 0 0.9 0 1.4 1.4 0.4 80 02075198 Dan River at Milton 2,328 1970, 1974, 1976-79 10 0 1.1 440 885 755 725 81 0207520780 Country Line Creek at SR 1 146 near 6.58 1974-81 17 0 0.9 0.3 1.5 1.4 1.1 Ashland 82 02075208 Country Line Creek near Locust Hill 22.6 1959, 1963, 1966, 1968 4 0 0.9 0.5 2.6 2.3 1.7 86 02075230 South Country Line Creek near 6.57 1953, 1959, 1963, 1966, 6 5 0.9 20 N/A2 N/A2 N/A2 Hightowers 1968, 1970 87 02075240 South Country Line Creek near Topnot 16.4 1962-69 20 8 0.9 0 0.1 <0.1 < 0. 1 88 02075250 Penson Creek near Yanceyville 12 2 1959, 1963-68, 1970 19 4 0.9 0 0.1 <0.1 < 0. 1 89 02075260 South Country Line Creek near Yanceyville 29.0 1949-53, 1956-60, 33 4 0.9 0 0.2 0.2 <0.1 1962-66, 1968 91 02075270 Country Line Creek near Semora 131 1954, 1956-68, 1970, 372 1 0.9 0.7 7.0 5.9 4.0 1973-74, 1974-84 94 0207718130 Hyco Creek at SR 1767 near Baynes 5.00 1974-81 19 0.9 0.1 0 <0.1 54 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina Table 7. Magnitude and frequency of annual low-flow characteristics at partial-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina (Continued) [mi2, square mile; water years, annual periods from October 1 to September 30; (ft3/s)/mi2, cubic feet per second per square mile; N/A, not available.] Number of Low-flow characteristics USGSdownstream (0 measure unitAverageannual numberorder £ in cubic feet per second Siteindexno. (0 Period of ments 32[(ft/s)/miflow] Station name o>0)c^ = record, cco E ' water years o o CM W7Q10 2 o O CM 6 0 r~O 0 LJ. § CO r§ 95 02077182 Hyco Creek near Hightowers 16.9 1959, 1963, 1966, 1968 4 2 0.9 20 N/A2 N/A2 N/A2 98 02077214 Reedy Fork Creek near Leasburg 9.29 1964-66, 1968, 1970 9 6 0.9 0 <0.1 0 <0.1 106 02077225 Hyco Creek near Roxboro 1 78.0 1949-54, 1956-59, 33 4 0.9 0 1.4 0 <0.1 1961-64 107 0207722510 Cobbs Creek near Leasburg 1.23 1965-66, 1968 4 1 0.9 20 N/A2 N/A2 N/A2 109 02077227 South Hyco Creek near Gordonton 10.5 1968, 1976, 1978-81, 24 2 0.9 0 0.4 0.4 0.3 1983-84 117 02077254 Richland Creek near Roseville 5.79 1964-66, 1968, 1970 8 2 0.9 0 <0.1 <0.1 <0.1 120 02077260 South Hyco Creek near Concord' 76.5 1953-54, 1956-64 28 1 0.9 <0.1 3.0 0.3 0.5 121 02077261 Sargents Creek near Ceffo 1.77 1965-66, 1968 4 0 0.9 0 0.2 0.2 0.2 135 02077331 Marlowe Creek at Longhurst 6.64 1953, 1963, 1968, 1970 6 3 0.9 <0.1 0.4 0.2 0.3 136 02077338 Marlowe Creek near Longhurst 10.9 1954, 1957, 1970, 1973 8 0 0.9 0.1 0.7 0.3 0.4 137 02077348 Marlowe Creek at SR 1322 near 20.6 1970, 1973-74, 1976, 56 0 0.9 40.2 1.4 0.5 0.8 Longhurst 1978, 1980-81, 1983-94 144 02077632 Mayo Creek near Gentrys Store 16.8 1959, 1963, 1966, 1968, 6 o 0.9 0 0.8 0.1 0.3 1970 145 02077644 Mill Creek near Gentrys Store 8.81 1959, 1963, 1966, 1968 4 2 0.9 0 0.6 <0.1 0.2 146 02077660 Mayo Creek near Woodsdale 1 52.7 1956-64, 1966, 1968 25 1 0.8 0 2.0 0.2 0.7 149 02078200 Aarons Creek near Oak Hill 27.6 1956-64, 1966, 1969 24 3 0.8 0 0.2 0 <0.1 154 02079100 Little Grassy Creek near Stovall 22.9 1956-59, 1961-64, 1966, 24 1 0.9 0 0.5 <0.1 0.2 1969 155 02079101 Grassy Creek at SR 1436 near Cornwall 61.2 1981, 1983-92 46 0 0.8 <0.1 1.8 0.2 0.8 158 0207920940 Gills Creek at SR 1430 near Stovall 13.8 1974-76, 1978-81, 43 2 0.8 0 0.2 <0.1 <0.1 1983-89 159 02079210 Island Creek near Bullock 33.1 1963-70 15 1 0.8 0 0.7 0.2 0.3 163 02079259 Nutbush Creek at SR 1 3 10 near Henderson 2.10 1970, 1973-76, 1978, 12 0 0.9 <0.1 0.3 0.2 0.2 1980 164 02079264 Nutbush Creek near Henderson 6.00 1970, 1973-74, 1976, 63 0 0.9 < 40.1 0.5 0.4 0.4 1978-79, 1981, 1983-94 166 0207966652 Smith Creek at SR 1224 near Ridgeway 2.56 1973-76, 1979 12 0 0.8 0 0.4 0.3 0.3 168 02079700 Smith Creek near Norlina 31.5 1954-63, 1966, 1969 22 0 0.8 <0.1 6.5 3.2 4.3 171 02079717 Smith Creek near Paschall 52.9 1954, 1961-62, 1966, 63 1 0.8 0.2 7.4 4.4 4.5 1973-74, 1976, 1979, 1981, 1983-94 175 02079750 Sixpound Creek near Oakville 12.1 1954, 1956-62 17 0 0.9 1.8 4.1 3.4 3.4 178 02079800 Big Stone House Creek near Littleton 1 16.0 1956-62 13 0 0.9 0.4 1.9 1.3 1.3 182 02080560 Chockoyotte Creek near Weldon 20.4 1961-62, 1965-70 11 0 1.0 0.4 1.4 1.0 0.9 Additional Tables 55 Table 7. Magnitude and frequency of annual low-flow characteristics at partial-record streamflow gaging stations in the Roanoke River Basin study area, North Carolina (Continued) [mi2, square mile; water years, annual periods from October 1 to September 30; (ffVs)/mr, cubic feet per second per square mile; N/A, not available.] Number of Low-flow characteristics SGSdownstream measure annualunitrerage d in cubic feet per second c numberorder Drainagearea ments 23/s)/miflow[(ft] X Period of 0) 2(mi) T3 Station name record, water years 0 CM ° 0) £ CM 0 § £ o CO | f- co ;> f- =3 N < 186 02080740 Quankey Creek near Halifax 31.7 1959-68, 1970 21 0 1.0 1.7 3.8 2.8 2.8 191 02080870 Gumberry Swamp near Jackson 20.0 1957, 1961, 1965-68 10 0 1.0 1.6 2.6 2.2 2 2 195 02081022 Roanoke River near Oak City 8,813 1969, 1972, 1983, 8 0 1.0 1,140 2,530 1,140 1,910 1986-87 199 02081050 Conoho Creek at Oak City 40.0 1959, 1964-66, 1968, 8 4 1.1 0 0 0 0 1970 201 02081065 Smithwick Creek near Beargrass 12.0 1959, 1965-68 7 2 1.1 0 <0.1 <0.1 <0.1 204 02081080 Ready Branch near Williamston 16.0 1949-54, 1957-59, 25 2 1.1 0.5 1.5 0.7 1.1 1963-64 206 02081096 Cashie River near Lewiston 19.2 1961, 1974-76, 1978, 18 8 1.1 0 <0.1 0 <0.1 1981, 1983-84 217 02081130 Roquist Creek near Windsor 60.1 1949-51, 1953-58, 1961 19 6 1.1 0 <0.1 0 0 Site now inundated by impoundment. Low-flow characteristics represent pre impoundment conditions. 'Estimates for all low-flow characteristics cannot be determined based on available data; however, multiple observations of zero-flow discharge at site or zero-flow 7Q10 discharge at downstream site allow estimate of zero-flow 7Q10 at indicated site. ^Records of discharge measurements at site 91 were combined with measurements at USGS station 0207527050 (site 92, drainage area 138 mi2 ) for determination of low-flow characteristics at site 91. 4Measurements made at this site include upstream point-source discharge; however, low-flow characteristics shown do not account for the effects of the point-source discharge. 56 Low-flow Characteristics and Profiles for Selected Streams in the Roanoke River Basin, North Carolina